BENIGN ODONTOGENIC TUMORS OF THE JAWS (AMELOBLASTOMA, ODONTOMA, CEMENTOMA): CLASSIFICATION, HISTOLOGICAL STRUCTURE, CLINIC, DIFFERENTIAL DIAGNOSIS, PRINCIPLES AND METHODS OF TREATMENT, PREVENTION OF COMPLICATIONS. NON ODONTOGENIC BENIGN TUMORS OF THE JAWS (OSTEOBLASTOMA, OSTEOMA, OSTEOIDOSTEOMA, CHONDROMA, FIBROMA, EPULIS, ETC.): CLASSIFICATION, HISTOLOGICAL STRUCTURE, CLINIC, DIFFERENTIAL DIAGNOSIS, TREATMENT, COMPLICATIONS.
Mandibular lesions
Mandibular lesions are myriad and common. The presence of teeth results in lesions that are specific to the mandible (and maxilla) and a useful classification that defines them as odontogenic or non-odontogenic. While it may ofteot be possible to make a diagnosis on imaging alone, this classification is helpful to narrow the differential.
Although a histological classification is probably the most scientifically sound, as radiologists, we are presented with an image, and therefore it is easier to classify lesions according to location in the mandible and their appearance. For a detailed classification of odontogenic tumours, many more than even the keenest neuro / head and neck radiologist can ever remember, please refer to the WHO classification scheme for odontogenic tumours (1992).
Below the lesions are divided into Cystic and Solid. Cystic should not be confused with lytic as solid radiolucent lesions can also appear lytic… (see lucent lesions of the jaw).
- periapical cyst (or radicular cyst) : common
- follicular cyst of the mandible (or dentigerous cyst) : common
- odontogenic keratocyst (OKC) : uncommon
- primordial cyst of the mandible
- Stafne cyst (or static bone cavity) : uncommon
- solitary bone cyst of the mandible (or traumatic or haemorraghic bone cysts)
- aneursymal bone cyst (ABC) : rare in the mandible
- residual cyst of the mandible
Benign
- odontoma : common
- ameloblastoma : relatively common
- odontogenic myxoma (looks just like an ameloblastoma) : rare
- calcifying epithelial odontogenic tumour (or Pindborg tumour) (looks just like an ameloblastoma) : rare
- cementoblastoma : rare
- ameloblastic fibroma
- adenomatoid odontogenic tumour : rare
Malignant
- odontogenic carcinoma (e.g ameloblastic carcinoma) : rare
- odontogenic sarcoma : rare
- odontogenic carcinosarcoma : rare
Benign
- cemento-ossifying fibroma
- juvenile ossifying fibroma
- exostosis (or torus mandibularis)
- osteoma
- fibrous dysplasia
- Paget’s disease
- neurofibroma
- schwannoma
- central giant cell granuloma (giant cell reparative cyst)
- osteosarcoma
- chondrosarcoma
- metastasis
- fibrosarcoma
- leiomyosarcoma
- lymphoma / leukemia
- multiple myeloma / plasmacytoma
- squamous cell carcinoma of mandible : common
Odontogenic tumor
An odontogenic tumor is a neoplasm of the cells or tissues that initiate odontogenic processes.
Examples include:
- Adenomatoid odontogenic tumor
- Ameloblastoma, a type of odontogenic tumor involving ameloblasts
- Calcifying epithelial odontogenic tumor
- Calcifying odontogenic cyst
- Dentigerous cyst
- Odontogenic keratocyst
- Odontogenic myxoma
- Odontoma
Adenomatoid odontogenic tumor
The adenomatoid odontogenic tumor is an odontogenic tumor[1] arising from the enamel organ or dental lamina.
Epidemiology
It is fairly uncommon, but It is seen more in young people. Two thirds of the cases are found in females.
Presentation and diagnosis
Two thirds of cases are located in the anterior maxilla, and one third are present in the anterior mandible.
Two thirds of the cases are associated with an impacted tooth (usually being the canine).
On radiographs, the adenomatoid odontogenic tumor presents as a radiolucency (dark area) around an unerupted tooth extending past the cementoenamel junction.
It should be differentially diagnosed from a dentigerous cyst and the main difference is that the radiolucency in case of AOT extends apically beyond the cementoenamel junction.
Radiographs will exhibit faint flecks of radiopacities surrounded by a radiolucent zone.
It is sometimes misdiagnosed as a cyst.
Treatment
Treatment can involve enucleation.
Ameloblastoma
Ameloblastoma (from the early English word amel, meaning enamel + the Greek word blastos, meaning germ[1]) is a rare, benign tumor of odontogenic epithelium (ameloblasts, or outside portion, of the teeth during development) much more commonly appearing in the lower jaw than the upper jaw.[2] It was recognized in 1827 by Cusack.[3] This type of odontogenic neoplasm was designated as an adamantinoma in 1885 by the French physician Louis-Charles Malassez.[4] It was finally renamed to the moderame ameloblastoma in 1930 by Ivey and Churchill.[5][6]
While these tumors are rarely malignant or metastatic (that is, they rarely spread to other parts of the body), and progress slowly, the resulting lesions can cause severe abnormalities of the face and jaw. Additionally, because abnormal cell growth easily infiltrates and destroys surrounding bony tissues, wide surgical excision is required to treat this disorder.
Subtypes
There are three main clinical subtypes of ameloblastoma: unicystic, multicystic, peripheral.[7] The peripheral subtype composes 2% of all ameloblastomas.[2] Of all ameloblastomas in younger patients, unicystic ameloblastomas represent 6% of the cases.[2] A fourth subtype, malignant, has been considered by some oncologic specialists, however, this form of the tumor is rare and may be simply a manifestation of one of the three main subtypes. Ameloblastoma also occurs in long bones, and another variant is Craniopharyngioma (Rathke’s pouch tumour, Pituitary Ameloblastoma.)
Clinical features
Ameloblastomas are often associated with the presence of unerupted teeth. Symptoms include painless swelling, facial deformity if severe enough, pain if the swelling impinges on other structures, loose teeth, ulcers, and periodontal (gum) disease. Lesions will occur in the mandible and maxilla,although 75% occur in the ascending ramus area and will result in extensive and grotesque deformitites of the mandible and maxilla. In the maxilla it can extend into the maxillary sinus and floor of the nose. The lesion has a tendency to expand the bony cortices because slow growth rate of the lesion allows time for periosteum to develop thin shell of bone ahead of the expanding lesion. This shell of bone cracks when palpated and this phenomenon is referred to as “Egg Shell Cracking” or crepitus, an important diagnostic feature. Ameloblastoma is tentatively diagnosed through radiographic examination and must be confirmed by histological examination (e.g., biopsy). Radiographically, it appears as a lucency in the bone of varying size and features—sometimes it is a single, well-demarcated lesion whereas it often demonstrates as a multiloculated “soap bubble” appearance. Resorption of roots of involved teeth can be seen in some cases, but is not unique to ameloblastoma. The disease is most often found in the posterior body and angle of the mandible, but can occur anywhere in either the maxilla or mandible.
Ameloblastoma is often associated with bony-impacted wisdom teeth—one of the many reasons some dentists recommend having them extracted.
Histopathology
Histopathology will show cells that have the tendency to move the nucleus away from the basement membrane. This process is referred to as “Reverse Polarization”. The follicular type will have outer arrangement of columnar or palisaded ameloblast like cells and inner zone of triangular shaped cells resembling stellate reticulum in bell stage. The central cells sometimes degenerate to form central microcysts. The plexiform type has epithelium that proliferates in a “Fish Net Pattern”. The plexiform ameloblastoma shows epithelium proliferating in a ‘cord like fashion’, hence the name ‘plexiform’. There are layers of cells in between the proliferating epithelium with a well-formed desmosomal junctions, simulating spindle cell layers.
A CT scan of a patient suffering from an ameloblastoma.
The resected left half of a mandible containing an ameloblastoma, initiated at the third molar
Variants
The six different histopathological variants of ameloblastoma are desmoplastic, granular cell, basal cell, plexiform, follicular, and acanthomatous.[8]
The acanthomatous variant is extremely rare.[9]
One-third of ameloblastomas are plexiform, one-third are follicular. Other variants such as acanthomatous occur in older patients.[2] In one center, desmoplastic ameloblastomas represented about 9% of all ameloblastomas encountered.
Ameloblastoma
Tracheal intubation is anticipated to be difficult in this child with a massive ameloblastoma.
Treatment
While chemotherapy, radiation therapy, curettage and liquid nitrogen have been effective in some cases of ameloblastoma, surgical resection or enucleation remains the most definitive treatment for this condition. In a detailed study of 345 patients, chemotherapy and radiation therapy seemed to be contraindicated for the treatment of ameloblastomas.[2] Thus, surgery is the most common treatment of this tumor. Because of the invasive nature of the growth, excision of normal tissue near the tumor margin is often required. Some have likened the disease to basal cell carcinoma (a skin cancer) in its tendency to spread to adjacent bony and sometimes soft tissues without metastasizing. While not a cancer that actually invades adjacent tissues, ameloblastoma is suspected to spread to adjacent areas of the jaw bone via marrow space. Thus, wide surgical margins that are clear of disease are required for a good prognosis. This is very much like surgical treatment of cancer. Often, treatment requires excision of entire portions of the jaw.
Radiation is ineffective[2] in many cases of ameloblastoma.[11] There have also been reports of sarcoma being induced as the result of using radiation to treat ameloblastoma.[12] Chemotherapy is also often ineffective.[12] However, there is some controversy regarding this[13] and some indication that some ameloblastomas might be more responsive to radiation that previously thought.[14][6]
While the Mayo Clinic recommends surgery for almost all ameloblastomas, there are situations in which a Mayo Clinic physician might recommend radiation therapy. These include malignancy, inability to completely remove the ameloblastoma, recurrence, unacceptable loss of function, and unacceptable cosmetic damage.[15] In the case of radiotherapy, oncologists at the Mayo Clinic would use intensity-modulated radiotherapy.[15]
Molecular biology
There is evidence that suppression of matrix metalloproteinase-2 may inhibit the local invasiveness of ameloblastoma, however, this was only demonstrated in vitro.[16] There is also some research suggesting that α5β1 integrin may participate in the local invasiveness of ameloblastomas.[17]
Recurrence
Recurrence is common, although the recurrence rates for block resection followed by bone graft are lower than those of enucleation and curettage.[18] Follicular variants appear to recur more than plexiform variants.[2] Unicystic tumors recur less frequently than “non-unicystic” tumors.[2] Persistent follow-up examination is essential for managing ameloblastoma.[19] Follow up should occur at regular intervals for at least 10 years.[20] Follow up is important, because 50% of all recurrences occur within 5 years postoperatively.[2] Recurrence within a bone graft (following resection of the original tumor) does occur, but is less common.[21] Seeding to the bone graft is suspected as a cause of recurrence.[19] The recurrences in these cases seem to stem from the soft tissues, especially the adjacent periosteum.[22] Recurrence has been reported to occur as many as 36 years after treatment.[23]
To reduce the likelihood of recurrence within grafted bone, meticulous surgery[21] with attention to the adjacent soft tissues is required.[22][19]
Epidemiology
The annual incidence rates per million for ameloblastomas are 1.96, 1.20, 0.18 and 0.44 for black males, black females, white males and white females respectively.[24] Ameloblastomas account for about one percent of all oral tumors[12] and about 18% of odontogenic tumors.[25] Men and women tend to be equally affected, although women tend to be 4 years younger than men when tumors first occur and tumors appear to be larger in females.
Calcifying epithelial odontogenic tumor
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The calcifying epithelial odontogenic tumor, also known as a Pindborg tumor or CEOT, is an odontogenic tumor first recognized by the Danish pathologist Jens Jørgen Pindborg in 1955.[1] It was previously described as an adenoid adamtoblastoma, unusual ameloblastoma and a cystic odontoma.[1] Like other odontogenic neoplasms, it is thought to arise from the epithelial element of the enamel origin.[1]
It is a typically benign and slow growing, but invasive neoplasm.[1][2] Intraosseous tumors (tumors within the bone) are more likely (94%) versus extraosseus tumors (6%).[2] It is more common in the posterior mandible of adults,[2] typically in the 4th to 5th decades. There may be a painless swelling, and it is often concurrent with an impacted tooth. On radiographs, it appears as a radiolucency (dark area) and is known for sometimes having small radiopacities (white areas) within it. In those instances, it is described as having a “driven-snow” appearance. Microscopically, there are deposits of amyloid-like material. The underlying nature of the amyloid-material is still unresolved.[2] Clinically it has two types, the central and the peripheral. The central type of the CEOT occurs in individuals ranging in age from 20–60 years. Two-thirds of the lesions are in jaws, more commonly in the molar area with a tendency to occur in the pre-molar areas.[2] It appears clinically to be a slowly enlarging painless mass. In the maxilla it can cause proptosis, epistaxis and nasal air way obstruction.
The peripheral type is commonly found in the anterior region of the maxilla and occurs as a soft tissue swelling. Histopathology will reveal prominent intercellular bridges and nuclear changes such as pleomorphism, hyperchromatism and prominent nucleoli. The mitotic figures are rare. Spread throughout the epithelium and connective tissue are spherical amorhpous calcifications.
The recurrence rate is 10-15%.[3] Franklin and Pindborg reported a recurrence rate of 14%.[4] It is considered to have a recurrence rate much lower than the recurrence rate for ameloblastoma.
Clear Cell Variant
When clear cells are present with clear cytoplasms, then this variant is referred to as “Clear Cell Variant” or CCEOT. The incidence of the clear cell variant is rare: according to this paper[5] written in 1994, there were only 9 known cases reported in the literature. However, this[6] indicates that approximately 8% of CEOTs contain clear cells. And Philipsen et al.[2] indicate that 15 cases of CCEOT have been reported so far (circa 2000).
Cystic Variant
There is one case reported in the literature of a 15-year old white male with a true cystic variant of CEOT.[7]
See also
Calcifying odontogenic cyst
Not to be confused with Odontogenic cyst or Glandular odontogenic cyst.
The calcifying odotogenic cyst, also known as the Gorlin cyst, is a cyst most likely to affect the anterior areas of the jaws. It is most common in people in their second to third decades but can be seen at almost any age. On radiographs, the calcifying odontogenic cyst appears as a unilocular radiolucency (dark area). In one-third of cases, an impacted tooth is involved. Microscopically, there are many cells that are described as “ghost cells“, enlarged eosinophilic epithelial cells without nuclei.
Clinical features
It can occur at any age,mostly between 2nd and 3rd decade of life. Diameter is 2 to 4 cm
Histopathology
In general, the epithelium seen is of stratified squamous type and is 2–3 cells thick. Additionally, focal areas of stellate reticulum like cells are seen and near the basement membrane ameloblast-like cells may be seen. Each type of COC shows special features:
Of three types: 1)Type 1A Ghost cells plus dentinoid are seen
2)Type 1B Formation of calcified tissues in the lumen of the cyst wall –> Dystrophic Calcification. Proliferation of tissue similar to an Ameloblastic Fibroma.
3)Type 1C Ameloblast like proliferation in the connective tissue and lumen of the cyst may be seen.
Radiographic features
Unilocular radiolucency may be seen. irregular calcifications may be seen in some cases.
Dentigerous cyst
A dentigerous cyst or follicular cyst is an odontogenic cyst – thought to be of developmental origin – associated with the crown of an unerupted (or partially erupted) tooth. The cyst cavity is lined by epithelial cells derived from the reduced enamel epithelium of the tooth forming organ. Regarding its pathogenesis, it has been suggested that the pressure exerted by an erupting tooth on the follicle may obstruct venous flow inducing accumulation of exudate between the reduced enamel epithelium and the tooth crown.
In addition to the developmental origin, some authors have suggested that periapical inflammation of non-vital deciduous teeth in proximity to the follicles of unerupted permanent successors may be a factor for triggering this type of cyst formation.
Histologically a normal dental follicle is lined by enamel epithelium, whereas a dentigerous cyst is lined by non-keratinized stratified squamous epithelium. Since the dentigerous cyst develops from follicular epithelium it has more potential for growth, differentiation and degeneration than a radicular cyst. Occasionally the wall of a dentigerous cyst may give rise to a more ominous mucoepidermoid carcinoma. Due to the tendency for dentigerous cysts to expand rapidly, they may cause pathological fractures of jaw bones.
The usual radiographic appearance is that of a well-demarcated radiolucent lesion attached at an acute angle to the cervical area of an unerupted tooth. The border of the lesion may be radiopaque. The radiographic differentiation between a dentigerous cyst and a normal dental follicle is based merely on size. Radiographically, a dentigerous cyst should always be differentiated from a normal dental follicle. Dentigerous cysts are the most common cysts with this radiographic appearance. Radiographically the cyst appears unilocular with well defined margins and often sclerotic borders. Infected cysts show ill-defined margins.
The most common location of dentigerous cysts are the Mandibular 3rd Molars and the Maxillary Canines, and they rarely involve deciduous teeth and are occasionally associated with odontomas.
Keratocystic odontogenic tumour
A keratocystic odontogenic tumour (also keratocystic odontogenic tumor), abbreviated KCOT,[1] is a rare and benign but locally aggressive developmental cystic neoplasm. It most often affects the posterior mandible.
It was previously called odontogenic keratocyst and abbreviated OKC.
Diagnosis
The definitive diagnosis is by histologic analysis, i.e. excision and examination under the microscope.
Under the microscope, KCOTs vaguely resemble keratinized squamous epithelium;[3] however, they lack rete ridges and often have an artifactual separation from their basement membrane.
Etiology
KCOTs are thought to arise from the dental lamina and associated with impacted teeth. Multiple odontogenic keratocysts are a feature of nevoid basal cell carcinoma syndrome. Odotogenic Keratocysts are derived from the Remnants of the Dental Lamina.
Genetics
Sporadic (non-syndromic) and syndromic KCOTs are associated with mutations in the gene PTCH, which is part of the Hedgehog signaling pathway.[1][4]
Symptoms
Swelling is the most common presenting complaint; however, KCOTs may be asymptomatic and found incidentally on dental X-rays.[5]
Differential diagnosis
Radiologically
Histologically
Malignant transformation
Malignant transformation to squamous cell carcinoma may occur, but is unusual.[6]
Treatment
As the entity is quite rare, opinions among experts about how to treat KCOTs differ.
Treatment options:[1]
- Wide (local) surgical excision.
- Marsupialization – the surgical opening of the (KCOT) cavity and a creation of a marsupial-like pouch, so that the cavity is in contact with the outside for an extended period, e.g. three months.
- Curettage (simple excision & scrape-out of cavity).
- Peripheral ostectomy after curettage and/or enucleation.
- Simple excision.
- Carnoy’s solution – usually used in conjunction with excision.
- Enucleation and cryotherapy
Classic look to a keratocyctic odontogenic tumor in the right mandible in the place of a former wisdom tooth. Unicystic lesion growing along the bone.
Massive keratocystic odontogenic tumour with impacted wisdom teeth superficial to lesion
Ameloblastoma
Overview
Ameloblastoma is a rare, noncancerous (benign) tumor that develops most often in the jaw near the molars. Ameloblastoma begins in the cells that form the protective enamel lining on your teeth.
Ameloblastoma occurs in men more often than it occurs in women. Though it can be diagnosed at any age, ameloblastoma is most often diagnosed in adults in their 40s or 50s.
Despite being benign, ameloblastoma can be very aggressive, growing into the jawbone and causing swelling and pain. Very rarely, ameloblastoma cells can spread to other areas of the body, such as the lymph nodes in the neck and the lungs.
Ameloblastoma is the most common type of odontogenic lesion.
Ameloblastomas (previously known as an adamantinoma of the jaw) are benign, locally aggressive tumours that arise from the mandible, or less commonly from the maxilla.
Epidemiology
Ameloblastomas are the second most common odontogenic tumour (odontoma is the most common) and account for up to a 3rd of such cases.
They are slow growing and tend to present in the 3rd to 5th decades of life, with no gender predilection 4.
Clinical presentation
Ameloblastomas typically occur as hard painless lesions near the angle of the mandible in the region of the 3rd molar tooth (48 and 38) although they can occur anywere along the alveolus of the mandible (80%) and maxilla (20%). When the maxilla is involved, the tumour is located in the premolar region, and can extend up in the maxillary sinus.
Although benign, it is a locally aggressive neoplasm with a high rate of recurrence. Approximately 20% of cases are associated with dentigerous cysts and unerrupted teeth.
Pathology
Ameloblastomas (not surprisingly) arise from ameloblasts, (part of the odontogenic epithelium, responsible for enamel production and eventual crown formation).
Three variants are described:
- simple (no nodule) – best prognosis
- luminal – single nodule projecting into the cyst
- mural – multiple nodules (often only microscopic) in the wall of the cyst
Radiographic features
Plain film and CT
It is classically seen as a multilocualted (80%), expansile “soap-bubble” lesion, with well demarcated borders and no matrix calcification. Occasionally erosion of the adjacent tooth roots can be seen which is highly specific. When larger it may also erode through cortex into adjacent soft tissues.
MRI
In general ameloblastomas demonstrate a mixed solid and cystic pattern, with a thick irregular wall, often with papillary solid structures projecting into the lesion. These components tend to vividly enhance.
Treatment and prognosis
Ameoloblastomas tend to be treated by surgical en-bloc resection. Local curettage is associated with a high rate of local recurrance (45 – 90%).
Simple unicystic lesions are less common but have a better prognosis. Simple (no nodule) variant will not be diagnosable on radiography, as it will be indistinguishable form other more common cysts. Luminal variant, has a single nodule projecting into the cyst. Mural variant has multiple nodules (often only microscopic) in the wall of the cyst. The latter has an elevated risk of recurrence.
Malignant behaviour is seen in two forms 5:
1. ameloblastic carcinoma
o frankly malignant histology
2. malignant ameloblastoma
o metastases despite well differentiated ‘benign’ histology
Differential diagnosis
General imaging differential considerations include
- dentigerous cyst – the relationship between ameloblastomas and dentrigerous cysts is a controversial one: 20% of ameloblastomas thought to arise from pre-existing dentigerous cysts
- odontogenic keratocyst (OKC) – usually unilocular with thin poorly enhancing walls
- odontogenic myxoma – can be almost indistiguishable
- aneurysmal bone cyst (ABC)
- fibrous dysplasia
Odontogenic myxoma
The odontogenic myxoma is an uncommon benign odontogenic tumor arising from embryonic connective tissue associated with tooth formation.[1] As a myxoma, this tumor consists mainly of spindle shaped cells and scattered collagen fibers distributed through a loose, mucoid material.
Clinical Presentation
Odontogenic myxomas have been found in patients ranging in age between 10 and 50 years, however, they are most commonly diagnosed in young adults (specifically between 25 and 35 years of age).[3][4] The mandible is more likely to be affected than the maxilla. The region between the molar and premolar is the site of most common occurrence for multilocular lesions[4] while the anterior portion of the mouth favors a smaller, unilocular variety.[3]
Patients afflicted with an odontogenic myxoma generally notice a painless, slowly enlarging expansion of the jaw with possible tooth loosening or displacement.[3] As the tumor expands, it frequently infiltrates adjacent structures. Maxillary lesions frequently enter the sinuses while mandibular tumors often extend into the ramus.[1]
Radiographic Presentation
Radiographically, odontogenic myxomas appear most commonly as multilocular radiolucencies with ill-defined borders, though unilocular cyst-like tumors can occur, especially when associated with impacted teeth or when discovered in childhood.[4][5] Ideally, the septa that cause the multilocular feature are thin and straight, producing a tennis racket or stepladder pattern. In reality, the majority of the septa visible in the tumor are curved and coarse, causing a “soap bubble” or “honeycomb” appearance, though locating one or two straight septa can aide in the diagnosis of this tumor.[1][5]
Treatment
Small unilocular lesions have been successfully treated with enucleation and curettage followed by chemical bone cautery. Multilocular tumors exhibit a 25% recurrence rate and, therefore, must be treated more aggressively. In the case of a multilocular myxoma, resection of the tumor with a generous portion of surrounding bone is required. Because of the gelatinous nature of the tumor, it is crucial for the surgeon to remove the lesion intact so as to further reduce the risk of recurrence.
Odontoma
The odontoma is a hamartoma[1] of odontogenic origin.[2]
The average age of people found with an odontoma is 14,[3] and the condition is frequently associated with an unerupted tooth.
In 2011; 66% of odontogenic tumors are odontomas (University of Louisville School of Dentistry). 22% of odontogenic tumors are odontomas.
Classification
There are two types: compound and complex.[5]
- A compound odontoma still has the three separate dental tissues (enamel, dentin and cementum), but may present a lobulated appearance where there is no definitive demarcation of separate tissues between the individual “toothlets”. It usually appears in the anterior maxilla.
- The complex type is unrecognizable as dental tissues, usually presenting as a radioopaque area with varying densities. It usually appears in the posterior maxilla or in the mandible.
Treatment for both compound and complex odontoma is removal by an oral surgeon.
Related articles
Odontogenic lesions
General reading
Pathology
- lucent
- periapical cyst (radicular cyst)[+]
- paradental cyst[+]
- dentigerous cyst (follicular cyst)
- lateral periodontal cyst
- keratocystic odontic tumour (odontogenic keratocyst)
- ameloblastoma
- adenomatoid odontogenic tumour
- calcifying epithelial odontogenic tumour (Pindborg)
- glandular odontogenic cyst
- mineralised[+]
Treatment
Which treatment is best for your ameloblastoma depends on several factors. Your doctors will consider your tumor’s size and location, as well as the type and appearance of the cells involved. Your treatment team also considers your treatment goals and your personal preferences when making a treatment recommendation.
Treatment options may include:
- Surgery to remove the tumor. The goal of surgery is to remove the tumor and a thin margin of healthy tissue that surrounds it. Ameloblastoma often grows into the nearby jawbone, so oral and maxillofacial surgeons remove the affected portion of this bone. An aggressive approach to surgery reduces the risk that ameloblastoma will recur.
- Surgery to repair the jaw. If surgery involves removing a portion of your jawbone, reconstructive and plastic surgeons will repair the jaw. Surgeons work to restore your ability to eat and speak, as well as to improve the appearance of your jaw.
- Radiation therapy. Radiation therapy may be recommended in certain situations, such as in the case of a large tumor or one that shows signs of cancer. Radiation therapy may reduce the risk of the tumor recurring. When a tumor can’t be removed with surgery, radiation therapy may be the only treatment.
- Supportive care. A variety of professionals will work with you to help you maintain your quality of life during and after treatment for ameloblastoma. At Mayo Clinic, these professionals may include dietitians, speech therapists, swallowing therapists, physical therapists, and specialists who make artificial replacements for missing teeth or other damaged natural structures in the mouth (prosthodontists).
Odontogenic Tumours
n General consideration
n Classification
n Description of some common and important odontogenic tumors.
n Odontogenic tumors comprise a complex group of lesions with varied histopathological and clinical features.
n Some tumors are true neoplasms, while some are hamartomas (developmental malformations).
n Some are composed only of odontogenic epithelium, while many are mixed i.e. both epithelium and mesenchyme, while some are composed only of mesenchyme
n CLASSIFICATION
A. TUMORS OF ODONTOGENIC EPITHELIUM: –
1. Ameloblastoma
2. Calcifying epithelial odontogenic tumor
3. Adenomatoid odontogenic tumor
4. Squamous odontogenic tumor
5. Clear cell odontogenic tumor
B. TUMORS OF ODONTOGENIC EPITHELIUM & MESENCHYME WITH / WITHOUT DENTAL HARD TISSUE FORMATION: –
1. Ameloblastic fibroma & Ameloblastic fibrosarcoma.
2. Ameloblastic fibro odontoma
3. Odontoameloblastoma
4. Odontoma – Compound & Complex
C. TUMORS OF ODONTOGENIC MESENCHYME WITH / WITHOUT DENTAL HARD TISSUE FORMATION: –
1. Odontogenic fibroma
2. Odontogenic myxoma
3. Cementoblastoma
4. Granular cell odontogenic tumor
AMELOBLASTOMA
n Most common odontogenic neoplasm, derived from odontogenic epithelium.
n Slowly growing, locally aggressive, benign neoplasm.
n Occurs in 3 different types with differing clinical, radiological and histological features.
1. CONVENTIONAL / MULTICYSTIC
2. UNICYSTIC
3. PERIPHERAL
AMELOBLASTOMA – CONVENTIONAL
CLINICAL FEATURES: –
Age incidence: 3rd & 4th decades.
Sex incidence: Slightly more in males.
Site predilection: 80% ameloblastomas occur in posterior mandible, followed by maxillary molar region.
Signs & symptoms: –
n Slowly growing, painless, hard bony swelling or expansion of jaw.
n Thinning of cortical plates produces “Egg shell crackling”.
n Other symptoms – Tooth mobility root resorption and paresthesia if inferior alveolar nerve is affected.
RADIOLOGICAL FEATURES: –
n Typically rounded, well defined multilocular radiolucency with scalloped margins.
n When loculations are large, the appearance is called as “SOAP BUBBLE” appearance.
n When loculations are smaller, the appearance is called “HONEY COMBED” appearance.
n Buccal & lingual cortical plates are expanded.
n Roots of adjacent teeth displaced / resorbed.
n As it spreads through medullary spaces, radiographic margins are not accurate indication of bone involvement.
DIFFERENTIAL DIAGNOSIS: –
1. ODONTOGENIC KERATOCYST
2. FIBROUS DYSPLASIA
3. OSSIFYING FIBROMA
4. CENTRAL GIANT CELL GRANULOMA.
HISTOPATHOLOGICAL FEATURES: –
Many subtypes are seen.
1. FOLLICULAR
2. PLEXIFORM
3. ACANTHOMATOUS
4. GRANULAR CELL
5. DESMOPLASTIC
6. BASAL CELL TYPE
7. CLEAR CELL TYPE
AMELOBLASTOMA (FOLLICULAR)
n Islands of epithelium resemble dental organ surrounded by mature connective stroma.
n Individual follicles show central mass of stellate reticulum like cells surrounded by a single peripheral layer of ameloblast like cells.
n Nuclei of peripheral cells are reversely polarized.
n Within the islands, cyst formation is common.
AMELOBLASTOMA (PLEXIFORM)
n Instead of islands, long, anastomosing cords and occasional sheets of epithelial cells bounded by columnar / cuboidal cells.
n Cells within cords are more loosely arranged than peripheral cells.
n Supporting stroma is loose and vascular.
n Cyst formation occurs, not inside follicles, but in surrounding stroma.
AMELOBLASTOMA (ACANTHOMATOUS)
n Central area of follicles show extensive squamous metaplasia, often associated with keratin formation.
n DOEAS NOT INDICATE A MORE AGGRESSIVE COURSE OF TUMOR.
n Can be confused with squamous cell carcinoma.
AMELOBLASTOMA (GRANULAR CELL)
- Follicles / sheets of cells show granular cell change.
n These cells have abundant cytoplasm filled with eosinophilic granules.
n Seen in younger persons and appears to be more aggressive clinically.
AMELOBLASTOMA (DESMOPLASTIC)
n This variant is composed of small islands / cords of odontogenic epithelial cells surrounded by a dense, collagenized stroma.
n Peripheral ameloblast like cells are missing / inconspicuous around the islands / cords.
n Occurs in anterior jaw and radiologically looks like a fibro-osseous lesion due to mixed opacity & lucency.
AMELOBLASTOMA (BASAL CELL)
n Least common type.
n Composed of nests / sheets of hyperchromatic basaloid cells.
n No stellate reticulum present centrally and peripheral cells tend to be cuboidal rather than tall columnar.
TREATMENT: –
n Can vary from simple enucleation to curettage to en bloc resection.
n As lesion spreads through medullary spaces, simple enucleation can leave islands of tumor within the jaws, leading to recurrence.
n Marginal resection is the optimal method.
n Rarely can undergo malignant transformation.
UNICYSTIC AMELOBLASTOMA
n Controversy, whether it arises de novo or as neoplastic transformation of odontogenic cyst lining.
CLINICAL FEATURES: –
Age incidence: Young individuals.
Sex incidence: males.
Site predilection: 90% cases occur in post mandible.
Signs & Symptoms: Asymptomatic swelling of jaws. Many lesions contain a tooth inside.
RADIOLOGICAL FEATURES: –
n Typically seen as well defined, unilocular ‘lucency, many times surrounding the neck of impacted 38 or 48 – impossible to distinguish from dentigerous cyst.
n Occasionally, may be seen unassociated with teeth – then they nay be diagnosed as OKC or a radicular cyst.
DIFFERENTIAL DIAGNOSIS: –
1. Odontogenic cysts like – Dentigerous, OKC, radicular etc.
2. Odontogenic tumors like – Ameloblastoma, AOT, CEOT etc.
HISTOPATHOLOGICAL FEATURES: –
n Three variants are recognized.
1. LUMINAL UNICYSTIC
2. INTRALUMINAL UNICYSTIC
3. MURAL UNICYSTIC
UNICYSTIC – LUMINAL
n Tumor is confined to luminal surface of cyst.
n Seen as fibrous cyst wall with lining comprised totally / partially of ameloblastic epithelium, showing a basal layer of columnar / cuboidal reversely polarized cells.
n Overlying epithelial cells are loosely adhesive, resembling the stellate reticulum of dental organ.
UNICYSTIC – INTRALUMINAL
n This variant shows the tumor from cyst lining protruding into the lumen of cyst.
n Intraluminal projections resemble plexiform ameloblastoma in most cases, though not always.
UNICYSTIC – MURAL
n In this type, the fibrous wall of the cyst is infiltrated with typical follicular / plexiform ameloblastoma.
n Believed to be more aggressive than other two variants.
AMELOBLASTOMA (PERIPHERAL)
n Typically presents as non ulcerated, sessile / pedunculated gingival mass.
n Must be differentiated from other more common gingival swellings.
ADENOMATOID ODONTOGENIC TUMOUR
n Earlier, believed to be a variant of Ameloblastoma with glandular elements and was referred to as ADENOAMELOBLASTOMA.
n Now believed to be a separate entity and thought to arise from odontogenic epithelial cells.
CLINICAL FEATURES: –
Age incidence: Young individuals, 1st & 2nd decades.
Sex incidence: More in females, twice more.
Site predilection: Anterior aspect of maxilla.
Signs & symptoms:
n Small, asymptomatic lesion.
n Discovered accidentally during routine dental X-ray examination to ascertain cause for unerupted tooth.
n Larger lesions cause jaw expansion
RADIOLOGICAL FEATURES:
n Typical well defined unilocular ‘lucency attached to an impacted / unerupted tooth, usually canine (FOLLICULAR VARIETY).
n ‘Lucency extends past cervical region & must be distinguished from dentigerous cyst.
Extrafollicular – well defined ‘lucency not related to unerupted tooth.
n In both cases, ‘lucency may contain snowflake like radio opacities.
DIFFERENTIAL DIAGNOSIS: –
n Radiographic appearance can suggest following lesions for provisional diagnosis –
1. Unicystic ameloblastoma
2. CEOT
3. COC
HISTOLOGICAL FEATURES: –
n Lesion is composed of spindle shaped epithelial cells that form sheets, strands or whorls in a scanty stroma.
n Rosette like structures may show a central space which may be empty or contain some eosinophilic amyloid like material.
n Tubular duct like spaces are also seen which show a central space surrounded by reversely polarized cells.
CALCIFYING EPITHELIAL ODONTOGENIC TUMOUR
n Rare tumor, accounts for > 1% of all odontogenic tumors.
n Although odontogenic in origin, its histogenesis is uncertain.
n Tumor cells strongly resemble stratum intermedium of dental organ.
CLINICAL FEATURES: –
Age incidence: 3rd to 5th decades.
Sex incidence: Equal.
Site predilection: 75% cases occur in posterior mandible.
Signs & symptoms: Asymptomatic, slow growing swelling.
RADIOLOGICAL FEATURES:
n Commonly appears as a well defined, scalloped, uni/multilocular ‘lucency, usually associated with an impacted tooth.
n Lesion may also show presence of scattered radiopaque material within the ‘lucency.
DIFFERENTIAL DIAGNOSIS: –
1. Odontogenic cysts like dentigerous, OKC, etc.
2. Odontogenic tumors like Ameloblastoma, etc.
3. Other bony lesion like Central giant cell granuloma, Aneurismal bone cyst etc.
HISTOLOGICAL FEATURES: –
n Tumor shows discrete islands / sheets of polyhedral epithelial cells in a fibrous stroma.
n Nuclei show lot of size variation, even giant nuclei can be seen.
n Tumor islands also enclose large areas of eosinophilic, amorphous, amyloid like material
n The cell outlines of tumor epithelial cells are distinct and intercellular bridges may be noted.
n The amyloid like material usually calcifies to form concentric rings (LEISEGANG RINGS).
ODONTOMA
n Most common odontogenic tumor.
n Considered hamartomas, rather thaeoplasm.
n In a fully developed odontoma, mainly enamel and dentin along with variable amounts of pulp and cementum are seen.
CLASSIFICATION: –
n Odontomas are further sub classified into
– COMPOUND ODONTOMA
– COMPLEX ODONTOMA
n Both occur with equal frequency.
Compound – composed of multiple, small, tooth like structures.
Complex – composed of conglomerate mass of enamel and dentin with no anatomic relationship to tooth.
CLINICAL FEATURES : –
Age incidence: First 2 decades.
Sex incidence: None.
Site predilection: Anterior maxilla.
Signs & symptoms:
n Mostly asymptomatic, small, seldom exceeding the size of tooth missing in the region.
n Larger lesions may cause jaw expansion.
ODONTOMA (COMPOUND)
n Gross pathological specimen showing a mass of more than 20 tooth like malformed structures.
n ODONTOMA (COMPOUND)
RADIOLOGICAL FEATURES: –
n This type is composed of multiple, small tooth like structures.
n The entire mass appears surrounded by a radiolucent rim.
n An unerupted tooth is usually associated with both types of odontomes which impedes normal eruption of the tooth.
ODONTOMA (COMPLEX)
RADIOLOGICAL FEATURES:
n Complex odontoma comprises of a single conglomerate mass of tooth like material.
n It bears no anatomic resemblance to any tooth.
n Appears as a ‘opaque mass surrounded by a narrow ‘lucent rim.
ODONTOMA (COMPOUND)
HISTOLOGICAL FEATURES: –
n Microscopically, it shows discrete tooth like denticles in a fibrous stroma.
n Being a decalcified specimen, enamel appears as spaces around normal looking dentin and pulp which bear normal anatomic relationship to each other.
ODONTOMA (COMPLEX)
HISTOLOGICAL FEATURES: –
n Consist of largely tubular dentin enclosing clefts / hollow circular spaces that contained enamel prior to decalcification.
n Thin layer of cementum sometimes may be present at the periphery.
NONODONTOGENIC BENIGN TUMORS OF THE JAWS
1. Exostoses and Tori
2. Osteoma
3. Osteoid osteoma
4. Central hemangioma
5. Arteriovenous fistula
6. Neurogenic tumors (neurilemmoma, neurofibroma)
7. Traumatic neuroma
8. Chondroma
Tumor-Like and Reactive Lesions
1. Central giant cell granuloma
2. Fibrous dysplasia
3. Histiocytosis X
BENIGN NONODONTOGENIC TUMORS OF THE JAW
FIBRO-OSSEOUS TUMORS Ossifying Fibroma (Cemento-Ossifying Fibroma)
The ossifying fibroma is a benigeoplasm characterized by the replacement of normal bone by fibrous tissue and varying amounts of newly formed bone or cementum-like material, or both. As a result of histological similarities, ossifying fibroma, fibrous dysplasia, and cemento-osseous dysplasia are classified together as benign fibro-osseous lesions. The diagnosis of benign fibro-osseous lesions is based on clinical, radiographical, and histopathological correlation. Chromosomal abnormalities have been identified in the ossifying fibroma100-102; however, the molecular mechanisms that underlie the development of this tumor remain unknown. An ossifying fibroma usually presents as a painless, slow-growing, expansile lesion (Fig. 23-17, A). Although these fibromas occur over a wide age range, most cases occur in the third and fourth decades of life. Female predilection is definite. Ossifying fibromas are believed to be confined to the jaws and craniofacial complex.103 The mandible, particularly the premolar-molar region, is affected more commonly than the maxilla. Rare multicentric or familial ossifying fibromas, or both, have been reported.104,105 The radiographical appearance is typically a welldefined radiolucency with a variable degree of internal calcification (Fig. 23-17, B). The borders may be sclerotic. Larger mandibular lesions characteristically produce bowing of the inferior border (Fig. 23-17, C). Root displacement and, less commonly, root resorption may be seen. Histologically, these fibromas are composed of a fibrous stroma with bony trabeculae or cementum-like spherules, or both, evenly distributed throughout the stroma. The microscopical appearance may be indistinguishable from fibrous dysplasia. The recommended treatment of ossifying fibromas is complete surgical excision. They characteristically shell out from the surrounding bone with ease. Reported rates of recurrence have ranged from less than 1% to 63%.106-114 In light of the potential for recurrence, some authors advocate more extensive surgery for more aggressive lesions and lesions involving the craniofacial bones.107,115,116 Ossifying fibromas do not display an infiltrative pattern into bone and therefore require smaller margins than the 1 cm typically required for an ameloblastoma, odontogenic myxoma, or a calcifying epithelial odontogenic tumor. Involved teeth with evidence of resorption should be removed with the lesion.
Fig. 23-16 An ameloblastic fibroma in a 26-year-old female. A, Presenting on a panoral radiograph, as a well-defined radiolucency displacing teeth. B, Histological appearance. Note islands of odontogenic epithelium in a loose myxomatous matrix. C, After it has been de-roofed but before enucleation. D, As a cream-colored, lobulated specimen following enucleation.
Fig. 23-17 Ossifying fibroma. A, Frontal view of a 21-year-old female demonstrating expansion of the right side of the mandible. B, Mixed radiolucent-radiopaque lesion of the mandible extending from the first molar region on the right to the first premolar region on the left, producing a bowing of the inferior border. C, Submental three-dimensional reconstructed computed tomography demonstrating the expansion of the mandible.
Juvenile Ossifying Fibroma (Juvenile Aggressive Ossifying Fibroma; Juvenile Active Ossifying Fibroma) The juvenile ossifying fibroma is considered by many to be a unique lesion because of its reported tendency to occur in children and adolescents, its more complex histological features, and its tendency for more aggressive growth. However, there is no general agreement among pathologists with respect to the proper terminology, histopathological features, or criteria for separating these lesions from conventional ossifying fibromas.117 Adding to the controversy are the facts that these lesions have beeoted in older patients and they are not always particularly aggressive. Two variants of the juvenile ossifying fibroma have been described—the trabecular variant118 and the psammomatoid variant.119 The trabecular variant has strands of immature cellular osteoid within the lesion and usually occurs in childhood with a slight maxillary predilection. The psammomatoid variant has small spherical ossicles surrounded by osteoid rims within the lesion. It occurs over a wider age range than the trabecular variant and usually affects the orbit or paranasal sinuses (Fig. 23-18). Although it is considered more aggressive than the more common ossifying fibroma that generally occurs at a later age, conservative excision is recommended for the juvenile ossifying fibroma. However, lesions involving the craniofacial bones may require more extensive surgery. Recurrence rates of 20% to 58% have been reported.117 Recurrences may be managed by local excision, and malignant transformation has not been reported.
LANGERHANS CELL DISEASE Langerhans cell disease was formerly known as histiocytosis X and before that as three separate diseases: eosinophilic granuloma, Hand-Schüller-Christian disease, and Letterer-Siwe disease. The clinical manifestations of these diseases range from solitary or multiple bone lesions to disseminated visceral, skin, and bone lesions. Despite their diverse manner of clinical disease expression, these three diseases are characterized by proliferation of Langerhans cells accompanied by varying numbers of eosinophils, other chronic inflammatory cells, and multinucleated giant cells. Langerhans cells, which are derived from the monocytic series, are found in the epidermis, mucosa, lymph nodes, and bone marrow. They are dendritic cells that process and present antigens to T lymphocytes. The etiology and pathogenesis of Langerhans cell disease remains unknown. Evidence suggests a neoplastic process,120 viral etiology, 121 and an overwhelming allergenic challenge.122 Langerhans cell disease generally affects children and young adults, although it may affect older adults. Three forms exist. Chronic localized Langerhans cell disease, formerly known as eosinophilic granuloma, refers to solitary or multiple bone lesions only (Fig. 23-19, A). Chronic disseminated Langerhans cell disease, formerly known as Hand-Schüller-Christian disease, is classically associated with a clinical triad of lytic bone lesions, exophthalmos, and diabetes insipidus (Fig. 23-19, B). Acute disseminated Langerhans cell disease, formerly known as Letterer-Siwe disease, usually affects infants and is multisystem iature, affecting the skin, bones, and internal organs, especially the lungs and liver. Bone lesions, either solitary or multiple, are the most common clinical presentation. Lesions most frequently involve the skull, mandible, ribs, and vertebrae, although almost any bone may be involved. Jaw lesions may produce pain and tenderness, tooth mobility, and expansion. Radiographically, jaw lesions usually appear as well-defined, punched-out radiolucencies, although they may be ill defined. Lesions often involve the alveolar bone, producing the classic appearance of “floating teeth.” The involved teeth remain vital; however, they often do not have adequate support and should not prevent biopsy of the tissue deep in the jaws that will be required for diagnosis.
The diagnosis of Langerhans cells disease may be confirmed using immunohistochemical studies. Langerhans cells stain positive for S-100 protein and CD1a antigen. In addition, Langerhans cells contain unique, rod-shaped cytoplasmic structures known as Birbeck granules, which are seen on electron microscopy. Accessible bone lesions of chronic localized Langerhans cell disease are usually treated with aggressive local curettage or resection with 5-mm margins where possible. Less accessible lesions may be treated with low-dose radiation therapy. Intralesional steroids have also been employed with some success,122 and cases of spontaneous regression have also been reported.123 It is necessary to evaluate these patients for additional bone or visceral involvement and to follow them for recurrence or disease progression. Individual lesions of chronic disseminated Langerhans cell disease may be treated as they are with the chronic localized form, but with widespread or visceral involvement, chemotherapy is often used. Acute disseminated Langerhans cell disease follows a rapidly progressive course and is treated with chemotherapy. The acute disseminated form is frequently fatal.
Fig. 23-18 Juvenile ossifying fibroma. A, Axial computed tomography of a 6-year-old male with an expansile mass of the right maxilla. B, Spherical ossicles in a cellular fibroblastic stroma.
Fig. 23-19 Langerhans cell disease. A, Chronic localized form of the disease producing a punched-out radiolucency seen at the mandibular alveolar crest in the region of the first premolar. B, Chronic disseminated form of the disease producing multiple mandibular radiolucencies.
LESIONS CONTAINING MULTINUCLEATED GIANT CELLS
A number of lesions occur within the jaws, with multinucleated giant cells as a prominent histological feature; however, their relationship to one another is ill defined. The lesions in this group are similar, if not identical, histologically, and they usually cannot be distinguished from one another solely on the basis of light microscopy. Clinical history, physical and radiographical examination, and serum biochemistry may be used to differentiate these lesions.
Central Giant Cell Granuloma The central giant cell granuloma is a benign proliferation of fibroblasts and multinucleated giant cells. This lesion was initially thought to represent a reparative process—thus it was termed a giant cell reparative granuloma.124,125 It is no longer considered to be reparative, and if left untreated the lesion will progress. The precise nature of the central giant cell granuloma remains speculative. It has been suggested that it may be an inflammatory lesion, a reactive lesion, a neoplasm, or an endocrine lesion. The proliferating cell in this lesion is the fibroblast, which is thought to produce cytokines, resulting in the recruitment of monocytes, which subsequently transform into multinucleated giant cells. Immunohistochemistry has shown the giant cells to be osteoclasts.126 Whether the central giant cell granuloma is unique to the jaws or whether it represents a continuum of the same disease process as giant cell tumors affecting the long bones is debatable and is discussed later. Central giant cell granulomas of the jaws are most often found in children and young adults, with up to 75% of cases occurring before 30 years of age. Females are affected twice as frequently as males. The lesion most often occurs anterior to the first permanent molar teeth. The mandible is affected three times more frequently than the maxilla, and the lesion may be seen to cross the midline. It most often produces painless expansion of the affected jaw; however, it may infrequently produce pain.
Radiographically, central giant cell granulomas may present as a unilocular or multilocular radiolucency that is usually well delineated (Fig. 23-20). On the basis of clinical and radiographical features, there appear to be two types of central giant cell granulomas. The first is the more common, nonaggressive lesion, which is asymptomatic, grows slowly, and does not produce cortical perforation or root resorption. The second is an aggressive lesion, which presents with pain, rapid growth, cortical perforation, and root resorption. The aggressive type may have a higher recurrence rate. Presently, no histopathological methods of differentiating the aggressive from the nonaggressive type exist. Histologically, the central giant cell granuloma contains few to many multinucleated giant cells in a background of fibroblasts with varying amounts of collagen. The multinucleated giant cells are often focally aggregated; however, they may be evenly distributed. Hemosiderin-laden macrophages and extravasated erythrocytes are commonly seen. Foci of osteoid may be seen, particularly at the periphery of the lesion. These histopathological features are similar, if not identical, to those seen in the brown tumor of hyperparathyroidism and cherubism. For years surgical curettage has been the treatment of choice. Surgical treatment has generally been associated with a recurrence rate of 15% to 20%, although recurrence rates as high as 50% have been reported.
Fig. 23-20 Central giant cell granuloma. Radiolucency of the anterior mandible seen to cross the midline in a 17-year-old male.
Recurrence risk and the fact that with large lesions even conservative curettage may be associated with the loss of teeth, damage to the inferior alveolar nerve, and sinus and nasal implications has led to the development of several nonsurgical treatments. The first nonsurgical treatment proposed was intralesional corticosteroid injections.127 Weekly injections of triamcinolone for 6 weeks have been shown to induce partial and in some cases complete resolution of the lesions.127-130 The mode of action of this treatment remains unknown. Subcutaneous calcitonin injections have also been used with some success.131-134 The injections are given daily for approximately 18 months. The mode of action of calcitonin remains speculative; however, some of the giant cells in these lesions have been shown to have calcitonin receptors.133 Thus the therapeutic effect of calcitonin may be mediated through inhibition of osteoclastogenesis. Alpha-interferon given by subcutaneous injection has also been advocated.135,136 The rationale for this therapy is that the antiangiogenic action of the alpha-interferon will suppress the angiogenic component of the lesion, resulting in resolution. In most cases surgery is still required after the alpha-interferon treatment; however, it may be less radical and there may be a reduced recurrence rate.
Giant Cell Tumor The giant cell tumor normally found in long bones is an aggressive lesion that some people believe is a variant of low-grade osteosarcoma. This tumor is generally believed to be an entity that is separate from the central giant cell granuloma of the jaws, although some authorities report it rarely occurs in the jaws. Histologically, it is similar to the central giant cell granuloma, although the giant cells are larger with more nuclei, the giant cells are more evenly distributed, the stroma is more cellular, and there may be areas of necrosis. However, in any particular case it may be difficult to make a distinction. The recurrence rate of giant cell tumors in long bones following curettage is higher than for central giant cell granulomas of the jaws, leading some authorities to advocate resection.
Hyperparathyroidism Hyperparathyroidism is characterized by the overproduction of parathyroid hormone (PTH). Primary hyperparathyroidism is the uncontrolled production of PTH as the result of a parathyroid adenoma, hyperplasia, or rarely an adenocarcinoma. Secondary hyperparathyroidism occurs in response to hypocalcemia, most often as a result of chronic renal failure. In both forms of hyperparathyroidism, excess PTH levels stimulate osteoclast-mediated bone resorption, which may produce a focal bone lesion known as a brown tumor of hyperparathyroidism. The lesion derives its name from the color of the tissue as seen on surgical exploration, which is a result of the erythrocyte extravasation and hemosiderin deposition within the lesion. Like the central giant cell granuloma, this lesion appears radiographically as a well-defined unilocular or multilocular radiolucency, and it commonly occurs in the jaws (Fig. 23-21). These lesions may be solitary or multiple. They are histologically identical to central giant cell granulomas. Patients with primary hyperparathyroidism are hypercalcemic, with associated signs and symptoms. In contrast, those with secondary hyperparathyroidism are hypocalcemic and those with central giant cell granulomas have normal serum calcium levels. Elevated serum PTH levels are associated with both forms of hyperparathyroidism. Additionally, laboratory studies in secondary hyperparathyroidism demonstrate impaired renal function. A 24-hour urinary calcium level can be measured to rule out benign familial hypocalciuric hypercalcemia, which is a hereditary condition that leads to hyperparathyroidism secondary to low renal sensitivity to parathyroid hormone. Normal PTH levels are found in association with central giant cell granulomas. Therefore it is prudent to obtain serum calcium and PTH levels in patients with giant cell lesions in order to exclude hyperparathyroidism. If a diagnosis of hyperparathyroidism is confirmed, treatment must be aimed at the cause and the lesions will usually resolve without any further treatment.
Fig. 23-21 Brown tumor of hyperparathyroidism. Multiple radiolucencies seen in the mandible of this patient with hyperparathyroidism.
Cherubism Cherubism is a rare hereditary condition characterized by painless, bilateral, symmetrical expansion of the jaws. It was first described in 1933, when it was named familial multilocular cystic disease of the jaws.137 It follows an autosomal dominant pattern of inheritance with 100% penetrance in males, 50% to 75% penetrance in females, and variable expressivity. A 2:1 male predominance exists. Sporadic cases have also been reported; these presumably represent spontaneous mutations. The genetic defect has been mapped to chromosome 4p16.3,138,139 which encodes the binding protein SH3 BP2.140-142 The lesions of cherubism commonly begin to manifest as painless, bilateral, symmetric expansion of the jaws between 2 and 5 years of age (Fig. 23-22, A), although milder forms may not be detected until a later age. The lesions are confined to the mandible and maxilla. The regions most often affected are the mandibular angle, ascending ramus, retromolar region, and maxillary tuberosity; however, in severe cases the entire mandible and maxilla may become involved. The mandibular condyles are always spared. With involvement of the maxillary contribution to the orbital floor, the globes may be displaced upward, resulting in scleral show. With eyes that appear to be turned upward and a round face, children with a severe form of this condition appear like cherubs depicted in Renaissance paintings. Radiographically, the involved bones show multilocular radiolucencies with thin and expanded cortices (Fig. 23-22, B). There may be premature exfoliation of primary teeth, as well as unerupted and displaced permanent teeth. Histologically, the lesions resemble the central giant cell granuloma. However, some lesions exhibit eosinophilic perivascular cuffing of collagen surrounding small capillaries throughout the lesion, allowing for differentiation between the two lesions.
Fig. 23-22 Cherubism. A, Frontal view of a 6-year-old male with bilateral facial expansion. B, Multilocular radiolucencies seen in the maxilla and mandible bilaterally. Note the sparing of the mandibular condyles.
The lesions of cherubism tend to enlarge until puberty, at which time they begin to regress. In the majority of cases, abnormal facial growth ceases and the lesions recalcify by age 30. Therefore treatment is usually conservative, allowing natural regression to occur. If surgical recontouring of expanded bone is necessary, it is best to defer it until after puberty. During childhood and early adolescence treatment should be directed toward assisting the eruption of teeth. As a result of the histologic similarity to central giant cell granuloma, calcitonin has been used in an attempt to cause resolution, but unlike the central giant cell granuloma it has not met with success, suggesting that cherubism lesions and central giant cell granuloma lesions are, in fact, different.143
Aneurysmal Bone Cyst The aneurysmal bone cyst is a pseudocyst characterized by blood-filled spaces in a connective tissue stroma containing multinucleated giant cells. The lesion occurs most commonly in the long bones and vertebrae. Within the craniofacial complex it is most common in the mandible, followed by the maxilla. The etiology and pathogenesis of the lesion remains unknown, although the lesion is generally regarded as reactive. Controversy remains over whether the lesion occurs as a primary entity or results from the development of a dilated vascular bed in a preexisting intrabony lesion. The peak incidence occurs within the second decade of life, with most occurring before 30 years of age. There is a slight female predilection. Mandibular and maxillary lesions most frequently occur in the molar regions. Patients often present with facial swelling that may develop fairly rapidly and can be associated with pain. The lesion usually appears radiographically as a multilocular radiolucency, although it may be unilocular (Fig. 23-23, A). There may be significant cortical expansion and thinning (Fig. 23-23, B).
Microscopically, sinusoidal blood-filled spaces of varying size are seen. These spaces are not lined by endothelium but are surrounded by a fibrous connective tissue stroma with variable numbers of multinucleated giant cells (Fig. 23-23, C). Osteoid and woven bone can often be seen within the lesion. Although some authors feel aneurysmal bone cysts are associated with a relatively high recurrence rate, curettage remains the treatment of choice. At the time of surgery lesional tissue appears like a “blood-soaked sponge”; however, significant hemorrhage is usually not encountered.
Fig. 23-23 Aneurysmal bone cyst. A, A radiolucent lesion seen to produce expansion of the mandibular left angle in a 13-year-old female. B, Coronal computed tomography demonstrating cortical expansion and thinning. C, Numerous small sinusoids surrounded by a connective tissue stroma and scattered multinucleated giant cells.
NEUROGENIC TUMORS Schwannoma (Neurilemmoma) The schwannoma is a slowly growing, benigeoplasm arising from Schwann cells of the nerve sheath (neurilemma). As this encapsulated tumor enlarges, it pushes the involved nerve aside without enveloping it. It most commonly occurs in the soft tissues of the head and neck, as well as the flexor surfaces of the upper and lower extremities. Intraosseous lesions are rare; however, the mandible is the most common site of occurrence for central lesions and maxillary lesions have been reported. Lesions may occur over a wide age range but are most common in young adults. Bony lesions may be asymptomatic or produce expansion, pain, paresthesia, tooth mobility, and tooth displacement. The usual radiographical appearance is that of a well-defined, unilocular radiolucency with a thin, sclerotic border. Histologically, this is an encapsulated spindle cell tumor that consists of variable amounts of two types of tissue, Antoni A and Antoni B. Antoni A tissue consists of spindle cells organized in palisaded whorls and waves around central acellular, eosinophilic areas termed Verocay bodies. Antoni B tissue consists of spindle cells randomly arranged within a loose, myxomatous stroma. The tumor is strongly S-100 protein positive. Intraosseous schwannomas can be treated by enucleation and curettage. When the lesion arises from an identifiable nerve such as the inferior alveolar nerve, it can be excised from the nerve while preserving the integrity of the nerve. Recurrences are rare.
Neurofibroma Neurofibromas arise from a mixture of cell types including Schwann cells and perineural fibroblasts. They may occur as solitary lesions or in association with neurofibromatosis. Neurofibromatosis is an autosomal dominant condition in which 50% of cases result from spontaneous mutation. Two types of this genetic disorder exist, neurofibromatosis type 1 (von Recklinghausen’s disease of skin) and neurofibromatosis type 2. Type 1 (
) is characterized by multiple cutaneous neurofibromas and café-au-lait spots in addition to several other features. Type 2 (
) is characterized by the development of bilateral vestibular schwannomas in more than 90% of individuals with the condition.
Peripheral neurofibromas occur rarely ieurofibromatosis type 2. Although most commonly reported in soft tissues, neurofibromas do occur in bone and have been reported in association with the inferior alveolar nerve. Pain or paresthesia may result from lesions of the inferior alveolar nerve. Patients may also present with cortical expansion. Intraosseous lesions may produce a welldemarcated or poorly defined unilocular or multilocular radiolucency. Adjacent soft tissue neurofibromas may produce cortical erosion. Solitary neurofibromas and those found in association with neurofibromatosis share the same microscopic features. The tumor is composed of spindle-shaped cells with fusiform or wavy nuclei in a delicate connective tissue matrix. It is not encapsulated and may blend with the adjacent connective tissues. Mast cells are characteristically scattered throughout the lesion.
A histological subtype known as a plexiform neurofibroma is highly characteristic of neurofibromatosis. The normally recommended treatment of solitary lesions following biopsy is localized excision. The lesions are often vascular, and extensive blood loss has been reported from surgical management of mandibular lesions; thus some authors have advocated mandibular resection. The number of neurofibromas that can occur with neurofibromatosis type 1 makes complete surgical therapy impractical. In these cases surgery is reserved for lesions that are large and symptomatic or compromise function, or both. Malignant transformation to neurogenic sarcoma occurs in 5% to 15% of neurofibromas associated with neurofibromatosis. Authorities believe that malignant transformation does not occur with solitary lesions. BOX 23-2Neurofibromatosis Type
1 A diagnosis is established when two or more of the following findings are present: 1. Six or more café-au-lait spots greater than 5 mm in diameter in prepubertal patients and greater than 15 mm in postpubertal patients 2. One plexiform neurofibroma or two or more neurofibromas of any type 3. Two or more pigmented iris hamartomas (Lisch nodules) 4. Axillary or inguinal region freckling 5. Optic nerve glioma 6. A distinctive osseous lesion such as dysplasia of the greater wing of the sphenoid or pseudoarthrosis 7. A first-degree relative with neurofibromatosis type
Neurofibromatosis Type 2
A diagnosis is established when one or more of the following findings are present: 1. Bilateral cranial nerve VIII masses 2. A first-degree relative with neurofibromatosis type 2 and either a single cranial nerve VIII mass or any of the following findings: Schwannoma Neurofibroma Meningioma Glioma Juvenile posterior subcapsular lens opacity
OSTEOID OSTEOMA AND OSTEOBLASTOMA The osteoid osteoma and osteoblastoma share the exact same histological features. They are distinguished from one another primarily by size, although there are also differences in sites of occurrence and associated symptoms. These are benigeoplasms, the etiology of which is unknown. Most cases occur in the second decade, with 85% to 90% occurring before 30 years of age. A 2:1 male predilection exists. The osteoid osteoma is less than 2 cm in diameter, occurring most frequently in the femur, tibia, and phalanges. Rarely it occurs in the jaws. An osteoid osteoma classically presents with nocturnal pain that is alleviated by aspirin. The osteoblastoma is greater than 2 cm in diameter, occurring most frequently in the vertebrae and long bones of the extremities. The craniofacial skeleton is the site of involvement in 15% of osteoblastomas. The mandible is affected more frequently than the maxilla. Within the jaws, the posterior tooth-bearing portion is the area most often involved. Clinically, it often develops relatively rapidly, producing swelling and pain. In contrast to osteoid osteomas, the pain is not typically nocturnal and it does not respond as well to aspirin. Radiographically, these lesions are usually well defined with a mixed radiolucent-radiopaque pattern (Fig. 23-24). A thin radiolucency may be noted surrounding a variably calcified central tumor mass. A zone of reactive sclerosis surrounding the lesion is a characteristic feature of the osteoid osteoma. Histologically, the osteoid osteoma and osteoblastoma are identical. Irregular trabeculae of osteoid and immature bone are seen within a cellular fibrovascular stroma. The osteoid trabeculae, which exhibit varying degrees of calcification, are surrounded by prominent osteoblasts. In some cases differentiation between osteoblastoma and low-grade osteosarcoma may be difficult. Treatment is generally confined to conservative surgical excision either with curettage or local excision. Reports have been made of some lesions regressing after incomplete excision or biopsy.144 Recurrences are rare but have been reported and may necessitate more aggressive treatment such as en bloc resection.145 Rare examples of malignant transformation have been reported.146,147 However, due to the possible difficulty in differentiating some osteoblastomas from osteosarcomas, some of these may represent an incorrect initial diagnosis.
OSTEOMA Osteomas are benign tumors composed of mature compact or cancellous bone. They are distinguished from the common palatal and mandibular tori, as well as buccal exostoses, despite identical histopathology. Tori and buccal exostoses are thought to be of developmental or reactive origin and not true neoplasms. Osteomas may arise from the surface of bone (periosteal osteoma), or they may be located in the medullary bone (endosteal osteoma). Osteomas may arise in the paranasal sinuses, skull bones, and facial bones including the maxilla and mandible. They most commonly develop in young adults. Periosteal osteomas most often present as slowgrowing, painless, discrete bony masses. Endosteal osteomas are usually asymptomatic and noted on routine radiographs. As a result of their location, some lesions may cause headaches, sinusitis, or ophthalmological complaints. Radiographically, osteomas appear as well-circumscribed, sclerotic masses. Two histological variants exist. One variant consists of normalappearing, dense, compact bone with sparse marrow tissue. The other form consists of lamellar trabeculae of cancellous bone with fibrofatty marrow. Osteoblastic activity is often prominent. Osteomas are usually solitary, except in cases of
CHONDROMA The chondroma is a benign tumor composed of mature hyaline cartilage. It most commonly occurs in the bones of the hands and feet, with rare occurrences in the craniofacial complex. Within the maxillofacial region, chondromas most often occur in the nasal septum and anterior maxilla. They have also been reported in the mandibular condyle, coronoid process, body, and symphysis. Chondromas typically present as painless, slowly progressive swelling. They usually appear before 50 years of age. There is no sex predilection. Radiographically, they appear as a unilocular or multilocular radiolucency, which may have internal foci of calcification. The lesions are composed of well-defined lobules of mature hyaline cartilage containing small chondrocytes with regular nuclei. The microscopic distinction between a benign chondroma and low-grade chondrosarcoma is difficult. Considering the rarity with which chondromas occur in the craniofacial complex, the difficulty in differentiating between a chondroma and a low-grade chondrosarcoma, and the aggressive nature of chondrosarcomas, one should question the diagnosis of a benign chondroma in the jaws. To avoid the potential risk of undertreating a malignancy, some authors consider chondromas of the jaws as potentially malignant and manage them accordingly. 151,152 These authors recommend wide surgical excision with 1-cm margins. If the lesion recurs following more conservative surgical treatment, the lesion should certainly be considered a low-grade chondrosarcoma and treated with wide surgical excision.
DESMOPLASTIC FIBROMA The desmoplastic fibroma is a benign, locally aggressive tumor of bone that is considered to be the osseous counterpart of soft tissue fibromatosis. The etiology and pathogenesis of this lesion remain unknown, although genetic, endocrine, and traumatic factors have been suggested. The lesion usually occurs in children and young adults, with most cases being discovered before 30 years of age. It most commonly occurs in the long bones but may occasionally affect the jaws. Within the jaws, the posterior mandible is the area most frequently involved. Patients most often present with a painless, slow-growing, firm swelling of the affected jaw. Radiographically, the lesion produces a radiolucency, which may be unilocular or multilocular (Fig. 23-25). The margins may be well defined or poorly defined. Cortical perforation and root resorption may be seen. Microscopically, the lesion is composed of interlacing bundles and whorled aggregates of densely collagenous tissue with spindled and elongated fibroblasts. The degree of cellularity may vary from one area of the lesion to another. Cellular atypia and mitotic figures are not seen. This lesion does not produce bone. Recurrence rates following conservative surgical treatment such as curettage and local excision are high, while lesions treated by resection or wide excision do not tend to recur.153,154 Thus despite a benign histology, the desmoplastic fibroma should be treated aggressively. Radiation155 and chemotherapy156,157 have been recommended for lesions involving vital structures and those located in areas where resection would be debilitating.
Mandibular tori seen bilaterally.
Torus palatinus as seen on a periapical film.
Mandibular torus
Osteoma of the compact bone arising from the mandibular cortex. It has to be differentiated from a calcified lymph node and a sialolith because of their similar radiographic appearance.
Osteoma arising from the angle of the mandible.
Osteoma of the mandible which is
attached by a pedicle and could be palpated clinically. This osteoma consists of a combination of cortical and cancellous bones. The osteoma should be differentiated from a sialolith.
Osteoma arising from the edentulous
alveolar bone. The osteoma is of
compact bone.
Osteoid osteoma in the region between the premolar and molar teeth
Central hemangioma involving the entire body of the mandible and showing a coarse trabecular pattern
Central hemangioma showing a
well-circumscribed cavity.
Arteriovenous fistula involving the whole palate
Neurilemmoma (schwannoma) involving the mandibular canal and the mental foramen. The lesion has a well-defined radiopaque border
Neurofibroma of the inferior dental nerve demonstrating a multilocular form
Traumatic neuroma associated with a fracture of the ramus. Note the fracture extending from the posterior border of the ramus
Traumatic neuroma associated with the extraction site of the mandibular first molar. Note the bulbous enlargement of the mandibular canal due to increased growth
Central giant cell granuloma exhibiting a multilocular radiolucency with a localized expansion of the jawbone
Central giant cell granuloma shows jaw expansion on an occlusal projection. The multilocular lesion crosses the midline of the mandible
Central giant cell granuloma in the midline region of the mandible
Central giant cell granuloma exhibiting a unilocular radiolucency with well-defined margins in the mandibular premolar region
Fibrous dysplasia presenting a “ground glass” appearance and an
unilateral expansion of the mandible
Fibrous dysplasia presenting a “ground glass” appearance
Fibrous dysplasia in the mature stage presenting a radiopaque image. The affected region is expanded
Fibrous dysplasia of the maxilla showing a mixed appearance of
radiopacities and radiolucencies.
Eosinophilic granuloma (histiocytosis X) destroying the periodontal bone around the roots of the maxillary first molar and giving the appearance of a
“floating tooth”.
Eosinophilic granuloma destroying the bone around the mandibular left
premolars and canine.
Eosinophilic granuloma in the apical region of the mandibular premolars
and first molar.
Hand-Schüller- Christian disease (histiocytosis X) showing multiple
radiolucent skull lesions giving the appearance of a geographic skull.
