Tumors
About 2000 to 3000 new cases of malignancies of the musculoskeletal system are diagnosed each year in the United States. The number of benigeoplasms is estimated to be about ten times this number. A timely diagnosis of malignant tumors reduces the likelihood of metastasis that dramatically reduces survival rates.
Evaluation
Evaluate tumors by taking the patient’s history, performing a careful physical examination, and obtaining necessary laboratory and imaging studies. The diagnosis of a tumor usually is made by the presence of pain, a mass, or a pathologic fracture. It may be an incidental finding (Fig. 1).
Figure 1.Presentations of tumors in children The common modes of presentation are with a mass, as in osteochondroma (green arrow); with pain, as in osteoid osteoma (orange arrow); with a pathologic fracture, as in osteosarcoma (red arrow); or as an incidental finding, such as this small nonossifying fibroma (yellow arrow).
History
Tumors usually present as a soft tissue mass, produce pain, or cause disability. How long a mass has been present is often difficult to determine from a history. Frequently, a large lesion, such as a slow-growing osteochondroma, is not noticed until shortly before the consultation. The family may incorrectly conclude that the tumor had grown quickly.
Pain is a more reliable indicator of the time of onset of a tumor. Inquire about the onset, progression, severity, and character of the pain. Night pain is common for both malignant tumors and some benign lesions, such as osteoid osteoma. Malignant lesions produce pain that increases over a period of weeks or months. Night pain in the adolescent is especially worrisome and should be evaluated first with a conventional radiograph. An abrupt onset of pain is usually due to a pathologic fracture. Such fractures most commonly occur through bone cysts typically found in the humerus and femur.
Age of the patient is helpful. A bone lesion in a child under age 5 years is likely to be due to an infection or eosinophilic gran–u–loma. Giant cell tumors and osteoblastomas occur in the late teen period.
Race is notable, as blacks seldom develop Ewing sarcoma.
Examination
The initial examination is usually performed for a mass or pain. Some lesions, such as osteochondromas, are usually multiple. Look for asymmetry, deformity, or swelling. Palpate for masses. If a mass is present, measure its size, assess for tenderness, and note any associated inflammation. Malignant tumors are typically firm, are nontender, and may produce signs of inflammation.
Imaging
Order imaging studies with a plan in mind (Fig. 2). Start with good-quality radiographs. Conventional radiographs remain the basic tool for diagnosis. Consider several features in assessment.
Figure 2.Flowchart for imaging primary bone tumors
Location Lesions tend to occur in typical locations both with respect to the bone involved (Fig. 3).
Figure3. Tumor types per site Less common tumors at each site are in parentheses. Asterisks (*) indicate malignant tumors. Based on Adler and Kozlowski (1993).
and the position in the bone (Fig. 4).
Figure 4. Typical locations for various tumors Note the location in the epiphysis, metaphysis, or diaphysis.
Effect of lesion Note the lesion’s effect on the surrounding tissue (Fig. 5).
Figure5. Diagnostic features by conventional radiography Note the effect of the lesions on bone (top), the effect oormal adjacent tissues (middle), and special diagnostic features (bottom).
Effect of lesion on bone Sharply punched out lesions are typical of eosinophilic granuloma. Osteolytic lesions are typical of most tumors; few are osteogenic on radiographs.
Effect oormal adjacent bone is useful in determining the invasiveness of the lesion. An irregular, moth-eaten appearance suggests a malignant lesion or an infection. A lesion that expands the adjacent cortex is usually benign and typical for aneurysmal bone cysts.
Diagnostic features suggest the aggressiveness of the lesion. Sclerotic margination suggests that the lesion is long-standing and benign. Periosteal reaction suggests a malignant, traumatic, or infectious etiology.
Special imaging Consider special types of conventional radiographs, such as for soft tissue or bone detail (Fig. 6).
Figure 6. High-resolution radiographs Compared to conventional radiography (left), note the increased bony detail shown by the high-resolution radiograph (red arrow).
Special studies may be essential to establish the diagnosis (Fig. 7).
Figure 7. Evaluation by imaging This child had foot pain and a negative radiograph (upper left). A month later, the patient was seen again because of increasing night pain. At that time, a bone scan showed increased uptake (yellow arrow), the radiograph showed increased density of the calcaneus (red arrow), a CT scan showed erosion of the calcaneus (orange arrow), and MRI showed extensive marrow involvement (white arrow). Ewing sarcoma was suspected by these findings.
CT scans are useful in assessing lesions of the spine or pelvis. Whole lung CT studies are highly sensitive for pulmonary metastases.
MRI is the most expensive diagnostic tool and is limited in young children due to the need for sedation or anesthesia. However, it is the most sensitive in making an early diagnosis and excellent for tissue characterization and staging of tumors, and should be made of all malignant soft tissue and bone tumors.
Bone scans are the next most useful diagnostic tools. These scans are helpful in determining whether a lesion is solitary or other lesions are present. The uptake of the lesion is important to note. A cool or cold scan suggests that the lesion is inactive, and only observation may be necessary. Warm scans are common in benign lesions. Hot scans suggest that the lesion is very active and that it may be either a malignant or benign lesion, such as an osteoid osteoma. Biopsy or excision is required.
Positive emission tomography PET scans are expensive but useful in evaluating malignant soft tissue and bone tumors, and especially in assessing the response to chemotherapy.
Laboratory
Complete blood count (CBC) is useful as a general screening battery and helpful in the diagnosis of leukemia.
C-reactive protein (CRP) is elevated in inflammatory conditions.
Erythrocyte sedimentation rate (ESR) is often elevated in Ewing sarcoma, leukemia, lymphomas, eosinophilic granuloma, and infection. ESR values rise more slowly and elevations persist for longer durations than CRP values.
Alkaline phosphatase (AP) values may be elevated in osteosarcoma, Ewing sarcoma, lymphoma, and metastatic bone tumors. The value of the study is limited because of the natural elevation of this value during growth, especially in the adolescent.
Biopsy
A biopsy is a critical step in management (Fig. 8) and should be performed thoughtfully by an experienced surgeon. In most cases, an open biopsy is appropriate. Needle biopsy is indicated for lesions located at inaccessible sites and for special circumstances. The biopsy should provide an adequate sample of involved tissue, and the tissue should be cultured unless the lesion is clearly neoplastic. The biopsy procedure should not compromise subsequent reconstructive procedures.
Figure 8. Biopsy principles Follow these basic principles during biopsy procedures.
Biopsies can be incisional, excisional, or compartmental in type (Fig. 9). Excisional biopsy is appropriate for benign lesions such as osteoid osteoma (Fig. 10) or for other lesions when the diagnosis is known before the procedure and the lesion can be totally–resected
Figure 9. Biopsy types These include incision, excision, and compartmental resection, depending upon the objective of the biopsy.
Figure 10. Excisional biopsy of osteoid osteoma The original lesion (red and white arrows) is excised in a block of bone. This block is divided in the operating room to make certain the entire lesion is removed. The nidus of the tumor is clearly seen (green arrow).
Staging
Staging of malignant tumors provides a means of establishing a prognosis. Prognosis depends on the grade of the lesion (potential for metastases), the extent and size of the lesion, and the response to chemotherapy. The extent of the lesion is categorized by whether the lesion is extracompartmental or intracompartmental (Fig. 11) and whether any distant metastases are present.
Figure 11. Staging of musculoskeletal tumors Staging is determined by the grade and extent of the lesion. Based on Wolf and Enneking (1996).
A knowledge of the response to chemotherapy (Fig. 12) helps the surgeon to determine the appropriateness of limb salvage procedures and how wide the surgical margins must be to avoid local recurrence following resection.
Figure 12. Response to chemotherapy The response to chemotherapy is helpful in determining the prognosis and subsequent management.
Differential Diagnosis
Differentiating myositis ossificans Differentiating bone tumors from myositis ossificans (MO) is sometimes difficult. MO lesions have reactive bone that is most active on the margins. MRI studies are rarely necessary, but will show an inflammatory lesion with a tumor core (Fig. 13).
Figure 13. Myositis ossificans Note that the lesion (white arrow) appears to be extracortical in origin and that the inflammatory mass (red arrow) does not include the bone.
Differentiating neoplasms, infection, and trauma Sometimes a child presents with pain (Fig. 14) and tenderness over a long bone (usually the tibia or femur). The radiographs may be negative or show only slight periosteal elevation. The differential diagnosis often includes osteomyelitis, a stress fracture, or Ewing sarcoma (Fig. 15). The evaluation usually requires a careful physical examination, radiographs, a bone scan, MRI, and a determination of the ESR and CRP.
Figure 14. Differentiating tumor, infection, and traumatic lesions Features of the lesion allow classification into diagnostic categories without the need for a biopsy.
Figure 15. Bone infections Sometimes unusual bone infections may be difficult to differentiate from tumors, such as a dia physeal lesion (red arrow) or osteomyelitis that extends across the physis (yellow arrow).
Unicameral Bone Cysts
Simple, solitary, or unicameral bone cysts (UBCs) are common lesions of unknown cause that generally occur in the upper humerus or femur (Fig. 16).
Figure 16. Unicameral bone cysts Common locations (red) and age pattern of involvement (blue) are shown.
Theories of etiology include a defect in enchondral bone formation or altered hemodynamics with venous obstruction, causing increased interosseous pressure and cyst formation. The cysts are filled with yellow fluid and lined with a fibrous capsule (Fig. 17).
Figure 17. Unicameral bone cyst lining This shows the synovial lining of a cyst wall.
Diagnosis
UBCs are most often first diagnosed when complicated by pain or a pathologic fracture (Fig. 18). Their radiographic appearance is usually characteristic. The lesions are usually metaphyseal, expand the bone, have well-defined margins, evoke little reaction, and appear cystic with irregular septa. Sometimes a fragment of cortical bone (called fallen leaf sign) can be seen in the bottom of the cavity.
Figure 18. Unicameral bone cysts in varied locations Note the typical active (red arrow) and inactive (yellow arrow) cysts with fractures. Flexible intramedullary rod fixation of an upper femoral cyst (orange arrow) is shown. A calcaneal cyst is an additional common site (white arrow).
Active cysts abut the growth plate and occur in children less than 10 to 12 years of age. They are more likely to recur after treatment and are associated with growth arrest that may follow a fracture.
Inactive cysts are separated from the plate by normal bone and usually occur in adolescents over 12 years of age.
Fractures are usually the presenting complaint. Sometimes the fracture line is difficult to separate.
Management Principles
Management is complicated by recurrence. The usual natural history of these cysts is to become asymptomatic following skeletal maturation. The objective of treatment is to minimize the disability when cysts are likely to fracture. These lesions are not precancerous.
Humeral cysts Place the child in a sling to allow the fracture to heal and to reestablish stability. Seldom does the effect of the trauma result in permanent healing of the cyst. Plan to manage the cyst by a series of injections (Fig. 19) with steroid, bone marrow, or bone matrix. Some doctors recommend breaking up the adhesion by forceful injections or perforating the septa with a trochar. Recurrence can be managed by repeated injections or curettage and grafting with autogenous or bank bone. Opinions differ regarding how aggressively recurrence is managed.
Figure 19. Steroid injection treatment This is the classic location for a unicameral bone cyst. This 12-year-old boy developed pain in the right upper arm; a radiograph showed the typical cyst with a pathologic fracture (red arrow). The lesion was treated by steroid injection (yellow arrow) with satisfactory healing (orange arrow). A year later, the cyst recurred (white arrow), but not to a degree that required additional treatment.
Femoral cysts are much more difficult to manage because of the load carried by the femur. Plan to curette and graft the cyst and stabilize the fracture with flexible intramedullary fixation. Complications include malunion with coxa vara and avascular necrosis with displaced neck fractures. This fixation is permanent and may prevent additional fractures even if some recurrent cyst formation occurs. An alternative approach is injection followed by spica cast protection for 6 weeks.
Calcaneal cysts are best managed by curettage and bone grafting. Small lesions may be treated by injection (Fig. 20).
Figure 20. Small calcaneal unicameral bone cyst This 14-year-old complained of pain and demonstrated a limp. X-rays demonstrated a small cystic lesion (red arrow). This was managed by perforating the cortex and septa with a trochar and injecting bone marrow.
Operative Management of Bone Cysts
Select management based on the child’s age; location, size, and position of the cyst in the bone; and previous treatment.
Selection of treatment method
Generally, injection treatment is appropriate for cysts of nonweight-bearing bones. Cysts of the proximal femur and large cysts in other sites of the lower limb may be managed by curettage and grafting.
Diagnosis
Confirm the diagnosis by inserting a #18 spinal needle into the cyst through the thinnest wall (Fig. 21 – А). Aspirate the cyst. Simple bone cysts are filled with clear yellow fluid. It may be slightly blood-tinged due to procedure. If no fluid is obtained, the lesion may be a solid tumor (Fig. 21 – В). Consider biopsy (Fig. 21 – C).
Injection treatment for unicameral cyst
If the cyst contains yellow fluid, perform a cystogram (Fig. 21 – D). Inject diluted contrast solution such as renografin to determine whether the cyst has single or multiple chambers (Fig. 21 – E). The options for injection treatment (Fig. 21 – F) include:
Steroid Inject 50–100 mg of methyl methylprednisolone based on the cyst size.
Autogenous bone marrow Aspirate about 50 cc from the posterior iliac crest. Mix with bone collagen slurry and inject the combination into the cyst.
Treatment of multilocular cysts
If only part of the cyst fills during the arthrogram (Fig. 21 – G), modify the plan.
Injection Inject each cavity with steroids or marrow (Fig. 21 – H) or break up the cyst.
Mechanical breakup of septa Percutaneously introduce a trochar into the cyst and break up the septa (Fig. 21 – I). Inject steroid or marrow as described above (Fig. 21 – J).
Figure 21.
Radiographs
The arthrogram often shows a venogram (Fig. 22). The cyst may fill completely (Fig. 23), or incompletely (Fig. 24).
Figure 22.
Figure 23.
Figure 24.
Curettage management
Manage cysts in weight-bearing bones, especially the upper femur (Fig. 25 – N), by curettage (Fig. 25 – O) and grafting. Following thorough curettage, fill cyst with autogenous or bank bone. Some recommend supplementing the curettage by freezing with liquid nitrogen, phenolization, or burning with an argon laser. The value of these supplemental measures has not been confirmed. Stabilize proximal femoral lesions with IM rods (Fig. 25 – P) or by nail-plate fixation (Fig. 25 – Q).
Complications
Recurrence and growth arrest of the upper humeral physis are most common. Growth arrest is usually due to the lesion, and usually following a fracture, not the surgery. Recurrence is common and requires long-term thoughtful management.
Figure 25.
Aneurysmal Bone Cysts
An aneurysmal bone cyst (ABC) is considered to be a pseudotumor possibly secondary to subperiosteal or interosseous hemorrhage or a transitional lesion secondary to some primary bone tumor.
Diagnosis
The diagnosis can usually be established by a combination of the location of the lesion, the age of the patient (Fig. 26),
Figure 26. Aneurysmal bone cysts Common locations (red) and age pattern of involvement (blue) are shown.
and the appearance on conventional radiographs (Fig. 27).
Figure 27. Aneurysmal bone cyst of the vertebral column
ABCs are eccentric, expansile, cystic lesions with a high recurrence rate. Lesions present in a variety of patterns and are sometimes difficult to differentiate from simple bone cysts (Fig. 28).
Figure 28. Classification of aneurysmal bone cysts. Types 1–5 are various common patterns of lesions of long bones. Based on Capanna et al. (1985).
Activity of the lesion The activity level can also be assessed by the appearance of the lesion’s margins.
Inactive cysts have intact, well-defined margins.
Active cysts have incomplete margins but the lesion is well defined (Fig. 29).
Figure 29. Aneurysmal bone cyst of the upper femur
Aggressive cysts show little reactive bone formation and poorly defined margins.
Other imaging is often necessary, especially in aggressive cysts. Fluid levels are common and can be seen on CT scans and MRI studies (Fig. 30).
Figure 30. Aneurysmal bone cyst of the pelvis Note the extensive lesion (red arrow) and the fluid level (yellow arrow) on the MRI
Management
Manage ABCs on the basis of the patient’s age, as well as the site and size of the lesion.
Spine About 10–30% of ABC lesions are in the spine. They most commonly occur in the cervical and thoracic levels. Lesions arise in the posterior elements but may extend to involve the body. Study posterior elements with CT and MRI preoperatively. The possible need for a combined approach, complete excision, and stabilization, as well as the risk of recurrence, complicates management.
Long bones Options include complete excision or saucerization, leaving a cortical segment intact, or curettage with cryotherapy or with a mechanical burr.
Pelvis Manage most lesions by curettage and bone grafting. Some recommend selective embolization. Be prepared for extensive blood loss.
Complications Bleeding can pose a significant problem.
Recurrence may require more aggressive management that might include more extensive excision. Expect a recurrence rate of 20–30% following curettage. Recurrence is 10-60% higher in children under 10 years of age.
Fibrous Tumors
Fibrocortical Defects
Fibrocortical defects (or fibrous metaphyseal defects), fibrous lesions that are the most common bone tumor, occur iormal children, produce no symptoms, resolve spontaneously, and are found incidentally. They occur at the insertion of a tendon or ligament near the epiphyseal growth plate, which may be related to the etiology. They have a characteristic appearance that is eccentric and metaphyseal, with scalloped sclerotic margins. These lesions often cause concern that sometimes leads to inappropriate treatment. Fortunately, the lesions have a characteristic radiographic appearance that is usually diagnostic. They are small, cortical in location, and well-delineated by sclerotic margins. They usually resolve spontaneously over a period of 1 to 2 years.
Nonossifying Fibroma
A larger version of the fibrocortical defect is called a nonossifying fibroma. These lesions are present in classic locations and are usually diagnosed during adolescence (Fig. 31).
Figure 31. Nonossifying fibroma Common (red) and less common (gray) locations are shown. Age pattern of involvement is shown in blue.
They are metaphyseal, eccentric with scalloped sclerotic margins (Fig. 32, 33), and may fracture when large or if present in certain locations. Manage most by cast immobilization. Resolution of the lesion occurs with time. Rarely, curettage and bone grafting are indicated if the lesion is unusually large or if a fracture through the lesion occurs with minimal trauma.
Figure 32. Nonossifying fibroma of the distal femur
Figure 33. Typical nonossifying fibroma These are typical features and locations (red arrows). Note the fracture line (white arrow) through the proximal tibia, with its origin in the fibroma.
Fibrous Dysplasia
Fibrous dysplasia includes a spectrum of disorders characterized by a common bony lesion. The neoplastic fibrosis replaces and weakens bone, causing fractures and often a progressive deformity. Ribs and the proximal femur are common sites, and the lesions are most common in adolescents (Fig. 34).
Figure 34. Fibrous dysplasia Common (red) and less common (gray) locations are shown. Age pattern of involvement is shown in blue.
Fibrous dysplasia can be monostotic or polystotic. The polystotic form is more severe and is more likely to cause deformity. This deformity is often most pronounced in the femur, where a “shepherd’s crook” deformity is sometimes seen (Fig. 35), and may show extensive involvement of the femoral diaphysis. Rarely, fibrous dysplasia is associated with café-au-lait skin lesions and precocious puberty, as described with Albright syndrome.
Medical management using drugs that inhibit osteoclastic activity have not been widely used in children but offer an alternative to surgical management.
Surgical management of fibrous dysplasia involves strengthening weakened bone using flexible intramedullary rods. Leave these rods in place indefinitely to prevent fractures and progressive deformity (Fig. 35).
Figure 35. Fibrous dysplasia of proximal femur These patients show a femur at risk for deformity (red arrow), varus deformity (yellow arrow), and intramedullary fixation to prevent deformity (orange arrow).
Benign Cartilagenous Tumors
Osteochondroma
Osteochondromas (osteocartilagenous exostoses) include solitary (Fig. 36) and multiple (Fig. 37) lesions.
Figure 36. Common locations of solitary osteochondromas
Figure 37. Multiple familial osteochondromas Note the widespread involvement. Based on data by Jesus-Garcia (1996).
The multiple form is inherited but thought to be due to a loss or mutation of two tumor suppressor EXT 1 and 2 genes. Lesions sometimes develop after chemotherapy and radiation therapy. Most tumors develop by enchondral ossification under a cartilage cap.
Diagnosis Osteochondromas are usually first noted as masses that are painful when injured during play (Fig. 38). These lesions are usually pedunculated but may be sessile. They may grow to a large size. Osteochondromas are so characteristic in appearance that the diagnosis is made by conventional radiographs.
Figure 38. Typical location for symptomatic lesions Lesions about the knee are frequently irritated and painful (red arrows).
Solitary Osteochondromas These lesions are most common in the metaphyses of long bones. They occur sporadically and present as a mass, often about the knee. Presentations in the spine may be associated with neurologic dysfunction.
Multiple Osteochondromas The common multiple form (Fig. 39) is inherited in an autosomal dominant pattern and is more common in boys. Multiple lesions about the wrist and ankle often cause progressive deformity (Fig. 40). Others may cause valgus deformities about the knee.
Figure 39. Multiple osteochondromas This child has multiple lesions (arrows).
Figure 40. Common deformities that cause disturbed growth These are common about the wrist (red arrow) and ankle (yellow arrow).
Management depends on the location and size of the tumor.
Pain is the most common indication for removal (Fig. 41). Often several lesions are removed in one operative setting. Complications of excision include peroneal neuropraxia, arterial lacerations, compartment syndromes, and pathologic fracture.
Figure 41. Removed osteochondroma This resected lesion is large and irregular.
Valgus knee can be managed by medial femoral or tibial hemistapling (Fig. 42) in late childhood.
Figure 42. Deformity correction Correction of knee and ankle valgus by placement of staples and medial malleolus screws.
Limb length inequality may require correction by an epiphysiodesis.
Wrist deformities result from growth retardation and bowing of the distal ulna. Management of these deformities is complex and controversial. Studies in adults show suprisingly little pain and functional disability, considering the magnitude of the deformity and the unsightly appearance.
Ankle deformities result from growth retardation of the distal fibula, producing ankle valgus. Studies in adults show significant disability and suggest that prevention or correction of tibiotalar valgus should be undertaken in late childhood or adolescence. Consider resecting the osteochondroma and performing an opening wedge osteotomy of the distal tibia to correct the valgus. When identified in childhood, consider placing a medial malleolar screw [F] to prevent excessive deformity. Deformities are often complex, and operative correction must be individualized.
Prognosis Very rarely, malignant transformation to chondrosarcoma occurs during adult life. This transformation is most common in solitary lesions, usually from lesions involving flat bones, and occurs about two decades earlier than primary chondrosarcomas. Most tumors are low grade. Because the transformation is very rare, prophylactic removal of exostoses is not appropriate.
Enchondroma
These cartilage tumors are located within bone. They are common in the phalanges and long bones and increase in frequency during childhood (Fig. 43). They produce the classic characteristic of cartilage tumors of speckled calcification within the lesion (Fig. 44).
Figure 43. Enchondromas Common (red) and less common (gray) locations are shown. Age pattern of involvement is shown in blue.
Figure 44. Ollier disease Note the extensive lesions of the distal femur and tibia (red arrows) with shortening and varus deformity.
Types There are several different types of enchondromas.
Solitary lesions occur most commonly in the hands (Fig. 45) and feet. Removal and grafting is indicated if the lesions cause disability.
Figure 45. Multiple enchondromas Note the extensive involvement of several fingers.
Ollier disease is a generalized disorder with cartilagenous enchondromas as one feature. Children with Ollier disease often have limb shortening and varus deformities (Fig. 44) involving one side of the skeleton. About one-fourth develop chondrosarcoma in adult life.
Maffucci syndrome is a rare disorder with subcutaneous hemangiomatas and multiple enchondromas. Malignant transformation is not uncommon in adult life.
Chondromyxoid Fibroma
This is a rare primary bone tumor that occurs mostly about the knee during the second decade. The radiographic appearance is often characteristic (Fig. 46) with an eccentric position, a sclerotic rim with lobulated margins, and prominent septa. Manage with local resection and grafting.
Figure 46. Chondromyxoid fibroma Note the characteristic features.
Chondroblastoma
These uncommon tumors occur in the epiphysis of long bones often during adolescence (Fig. 47). They occur most commonly in the upper humerus, femur, and tibia. They can be confused with infection or arthritis. They are aggressive and prone to recur. Treat by thorough curettage and possibly cryotherapy or phenolization and bone grafting. Operative injury to the growth plate or articular cartilage is due to the juxtaarticular location. Anticipate local recurrence in about 20% of lesions.
Figure 47. Chondroblastoma Common (red) and less common (gray) locations are shown in the drawing. Age pattern of involvement is shown in blue. Based on Schuppers (1998). Radiographs (below) show typical locations in the epiphysis of the greater trochanter (red arrow) and proximal tibia (white arrow). Note that the proximal tibial lesion is aggressive, as it crossed the physis (yellow arrow).
Dysplasia Epiphysialis Hemimelica
Dysplasia epiphysialis hemimelica (Trevor disease) is a rare cartilagenous tumor that arises from the growth plate or articular cartilage (Fig. 48).
Figure 48. Dysplasia epiphysialis hemimelica Note the swelling of the knee (red arrows) and ankle involvement (yellow arrow).
The most common sites of involvement are the distal tibia and the distal femur. Lesions often involve one side of the epihysis and may show multilevel involvement in the same limb. The diagnosis is often difficult early on, as the lesion is primarily cartilagenous and poorly imaged with conventional radiographs. MRI is helpful in showing the extent of the tumor and separating the lesion from the normal epiphysis or joint cartilage. Excise extraarticular lesions. Remove intraarticular lesions and correct secondary deformity with an osteotomy as necessary. Recurrence of the tumor is common, due to its periarticular location and extensive involvement of adjacent bone. Multiple resections throughout childhood are ofteecessary.
Osseous Tumors
Osteoid Osteoma
This benign, bone-producing, highly vascular tumor induces an intense bony reaction and a characteristic pain pattern. These tumors occur most commonly in long bones during the second decade (Fig. 49).
Figure 49. Osteoid osteoma Common (red) and less common (gray) locations are shown. Age pattern of involvement is shown in blue.
Diagnosis The pain typically occurs at night, is well localized, and is often relieved by aspirin. Spine lesions occur in the posterior elements of the spine and may cause secondary scoliosis. Lesions are tender and, if close to a joint, cause joint inflammation that may be confused with primary arthritis. Lesions may cause hemideossfication due to chronic pain and a limp (Fig. 50).
Figure 50. Osteoid osteoma Note the hemideossification of the left pelvis and femur. This is due to pain and limp over a period of months from a proximal femoral lesion.
The radiographic appearance is often characteristic for well-established lesions. A radiolucent nidus is surrounded by reactive bone (Fig. 51). The bone scan is diagnostic, with intense localized uptake at the nidus. Image with MRI and CT scans to fully evaluate the lesion.
Figure 51. Osteoid osteoma of the proximal femur Lesions are common in this location. Note the typical nidus (red arrow) surrounded by reactive bone. Lesions are very “hot” on the bone scan (yellow arrow).
Management New options for management supplement the traditional approach of open excision.
Antiinflammatory Lesions eventually resolve over many years. This option is rarely acceptable to families.
Percutaneous ablation using CT for localization and radio frequency ablation is preferred in most cases (Fig. 52).
Figure 52. Thermocoagulation of osteoid osteoma This lesion of the posterior elements (yellow arrow) is located in an ideal site for percutaneous ablation. Thermocoagulation was performed under CT imaging guidance (red arrow).
Open excision is a reasonable option but carries a significant risk of an incomplete resection and local recurrence.
Osteoblastoma
This benign bone-producing tumor is similar to the osteoid osteoma but larger and shows clear differences. Pain is less intense and not relieved by aspirin. Lesions are not surrounded by reactive bone. These lesions occur in the spine and long bones most frequently during the second decade (Fig. 53).
Figure 53. Osteoblastomas Common (red) and less common (gray) locations are shown. Age pattern of involvement is shown in blue.
One-third of these lesions occur in the spine (Fig. 54), causing back pain and often scoliosis and sometimes localized tenderness. Laboratory studies are normal. CT and bone scans are useful. They are sometimes difficult to differentiate from osteosarcoma. Spinal lesions are most difficult to manage because of the adjacent vertebral artery in a cervical spine lesion. Manage by complete resection. Expect a recurrence rate of about 20–30%.
Figure 54. Osteoblastoma of the sacrum
Miscellaneous Bone Tumors
Eosinophilic Granuloma
Eosinophilic granuloma is the localized form of Langerhans’ cell histiocytosis or histiocytosis X.
Diagnosis The peak age of onset is between 1 and 3 years of age (Fig. 55).
Figure 55. Eosinophilic granuloma Common (red) and less common (gray) locations are shown. Age pattern of involvement is shown in blue.
This tumor has been described as the “great imitator” of bone tumors. Lesions are painful and are most often confused with osteomyelitis or sometimes Ewing sarcoma. Lesions often appear “punched out” on conventional radiographs (Fig. 56, 57), but sometimes elicit periosteal reactions, suggesting a sarcoma.
Figure 56. Eosinophilic granuloma of the scapula This lesion is shown by CT scan (red arrow) and conventional radiograph (yellow arrow).
Figure 57. Eosinophilic granuloma in varied locations
The child may have a low-grade fever and elevated ESR and CRP, making the differentiation from an infection difficult. Consider ordering skull films because the skull is the most common site of bony involvement. Sometimes the diagnosis must be established by biopsy.
Management The natural history is of spontaneous resolution over a period of many months. Management options include simple observation, immobilization to improve comfort and reduce the risk of pathologic fracture, injection with steroid, limited curettage, or radiation treatment.
Spine lesions cause collapse (vertebra plana) and sometimes neurologic involvement. Manage by observation or brace immobilization. Rarely, curettage is necessary to hasten resolution.
Lower limb long-bone lesions, if large enough, may pose a risk of pathologic fracture. Curettage and cast protection may be appropriate.
Giant Cell Tumors
Giant cell tumors (GCT) are aggressive tumors that occasionally occur in adolescents. Lesions are usually metaphyseal or epiphyseal, eccentric, expansive, and show little sclerosis or periosteal reaction (Fig. 58). These tumors are locally invasive and often recur. Manage by curettage, thermoablation and grafting. Provide careful follow-up because recurrence develops in about a quarter of cases.
Figure 58. Giant cell tumor of bone These lesions (arrows) occurred shortly after the end of growth. Note the lack of periosteal reaction.
Neurofibroma
Neurofibromatosis causes widespread pathology (Fig. 59), including scoliosis, pseudoarthrosis of long bones, thoracic lordoscoliosis, protrusio acetabuli, and abnormal bone growth (see details in Chapter 16).
Figure 59. Neurofibromatosis Note the dural ectasia (red arrows).
Osseous Hemangioma
This is often present in the vertebrae or skull but may appear in the extremities (Fig. 60). Lesions are diffuse and suggest a malignant tumor (Fig. 61). Wide resection is necessary, and recurrence is common.
Figure 60. Hemangioma of bone This hemangioma involved the fifth matacarpal, which was painful clinically and destructive in its radiographic appearance (red arrows).
Figure 61. Hemangioma of bone These lesions (arrow) are often difficult to differentiate from malignant lesions.
Benign Soft Tissue Tumors
Hemangioma
Hemangiomas are common during childhood. They may be part of a systemic condition (Fig. 62) or an isolated lesion (Fig. 63).
Figure 62. Hemangioma This boy has Klippel-Weber-Trenaunay syndrome with extensive hemangioma and limb hypertrophy (red arrow).
Figure 63. Extensive thigh hemangioma This large lesion involves much of the medial thigh muscles (red arrows).
Diagnosis The clinical features depend on the location and size of the lesions. Subcutaneous lesions are usually locally tender. Intramus-cular lesions cause pain and fullness, and very large or multiple lesions may cause overgrowth or bony deformity.
Imaging Punctate calcification in the lesion is diagnostic. CT and MRI are most useful for diagnosis and preoperative planning.
Management Many patients are diagnosed clinically and treated symptomatically. Large and very painful lesions may require resection. Resection is often difficult, as the lesions are poorly defined and may be extensive. Recurrence is common.
Synovial Hemangioma
Hemangioma of the knee is a cause of pain and recurrent hemarthroses in the pediatric age group (Fig. 64). The diagnosis may be delayed and the condition misdiagnosed as an internal derangement of the knee. Historically, long delays in diagnosis have occurred. Conventional radiographs show soft tissue swelling. MRI is usually diagnostic. Diffuse lesions are difficult to excise arthroscopically, and open wide excision is often required. Recurrence is common.
Figure 64. Synovial hemangioma This child had a swollen knee with frequent bloody effusions. Repeated resections over a period of many years were required
Pigmented Villonodular Synovitis
These lesions are rare in children. They should be considered in the differential diagnosis of a hemarthrosis of joints. They occur in varied sites, may involve joints (Fig. 65) and tendon sheaths, can be multifocal, and may present as popliteal cysts. Manage by total synovectomy. Recurrence is common.
Figure 65. Pigmented villonodular synovitis This lesion presented with a pain and joint swelling.
Plantar Fibroma
Fibromas may occur in infants with a lump on the anteromedial portion of the heel pad. Most remain small and asymptomatic, some disappear, but most persist, and if painful require excision.
In the child, plantar fibroma usually occurs as nodular thickening of the plantar fascia (Fig. 66). Observe to determine the potential for enlargement. Resect enlarging lesions. Be aware that mitotic figures are common in the specimen. Recurrence is frequent, and overtreatment is common. Differentiating fibrosarcoma from desmoid tumors is difficult.
Figure 66. Plantar fibromatosis Note the plantar thickening with overlying thickening of the skin.
Other Tumors
A variety of other tumors occur in childhood, including lipomas (Fig. 67), lymphangiomas, and benign fibrous tumors.
Figure 67. Lipoma Note the large lipoma (red arrow) of the distal leg in a 16- month-old infant, and the smaller, more typical lesion in a subcutaneous location (yellow arrow) in a child.
Malignant Soft Tissue Tumors
These tumors account for about 7% of malignant tumors of childhood. About half are rhabdomyosarcomas. These soft tissue malignancies are divided into five general categories (Fig. 68). Features that suggest a soft tissue lesion to be malignant include being firm, deep, nontender, and greater than 5 cm in diameter.
Figure 68. Soft tissue sarcomas From data of Conrad et al. (1996).
Rhabdomyosarcoma
This is a sarcoma of the skeletal muscle. It is the most common pediatric soft tissue sarcoma (Fig. 69). Extremity tumors account for 20% and carry a poorer prognosis.
Figure 69. Rhabdomyosarcoma age distribution These tumors are common in infancy and early childhood.
Lesions are firm, nontender, and within the muscle compartment (Fig. 70). Tumors occur in childhood, and metastasize to lymph nodes and later to bone. Manage by total excision and chemotherapy. Expect the 5-year survival to be in the 65–75% range.
Figure 70. Rhabdomyosarcomas These tumors develop within muscle compartments (red arrow). Rarely, they spread to bone (yellow arrow).
Malignant Fibrous Tumors
Desmoid tumors or fibromatosis are sometimes considered to be benign. However, because of their high rate of recurrence, they are sometimes considered as low-grade fibrosarcomas. Most occur in the extremities, creating a soft tissue mass and sometimes erosion or deformity of the adjacent bone (Fig. 71). The natural history of fibromatoses is variable; lesions often recur and undergo spontaneous remission. Fibromatoses seldom metastasize or cause death.
Figure 71. Desmoid tumors Note the large soft tissue mass (red arrow) and deformation of the second proximal phalanx (yellow arrow).
Manage by total resection when possible. If surgical margins cannot be achieved without sacrificing the limb or its function, excisional resection is an acceptable alternative. The role of adjuvant chemotherapy is controversial. Radiation therapy is effective but often complicated by growth arrest when the radiation field includes centers of bone growth.
Synovial Sarcoma
These tumors occur most commonly in adolescents (Fig. 72) and adults. Most occur in the lower extremities. Primary metastases are usually to regional lymph nodes or the lungs. Manage by chemotherapy, nonmultilating resection, and radiation. Expect 70–80% survival.
Figure 72. Synovial sarcoma This lesion in a 16-year-old boy involving the elbow joint is poorly seen on conventional radiographs but readily imaged by MRI (red arrow).
Round Blue Cell Tumors
These tumors include primitive neuroectodermal tumors, soft tissue Ewing sarcomas, and Askin tumors. Askin tumors are round-cell tumors involving the central axis and chest wall.
Miscellaneous Sarcomas
Peripheral nerve sheath sarcomas Malignant degeneration occurs in 5–10% of patients with neurofibromatosis (NF1). Enlarging lesions in these patients should be documented by MRI and excised or biopsied.
Other sarcomas These include a variety of tumors (Fig. 73): leiomyosarcoma, liposarcoma, angiosarcoma, and many others.
Figure 73. Soft tissue malignancies in infants This liposarcoma (red arrow) and fibrosarcoma (yellow arrow) have become massive lesions.
Malignant Bone Tumors
The early diagnosis of malignant bone tumors is an important factor in improving survival. The features of osteosarcoma and Ewing sarcoma at presentation should be kept in mind (Fig. 74). A careful history and physical examination are important. Be aware that the history of pain is often intermittent, especially for Ewing sarcoma, and a misleading history of minor trauma is common. About a third of the patients present with a palpable mass.
Figure 74. Presenting features of childhood bone tumors Differences in presentation of the two common childhood bone tumors are shown. Based on Widhe B and Widhe T. JBJS 82A:667, 2000.
Osteosarcoma
Osteogenic sarcoma is the most common malignant tumor of bone. Primary osteosarcoma occurs in children and adolescents, with a peak incidence at age 14 years.
Diagnosis Osteosarcoma commonly occurs during the second decade of life and often occurs about the knee (Fig. 75).
Figure 75. Osteosarcoma Common (red) and less common (gray) locations are shown. The age of onset is shown in blue.
Pain with activities and a palpable mass are often early findings. Sometimes the patient presents with a pathologic fracture. Radiographs may show the classic features of an osteogenic lesion (Fig. 76).
Figure 76. Classic radiographic appearance of osteosarcoma These studies show the classic osteogenic features of the lesion in the most common location
Lesions may be either an osteolytic or osteogenic lesion of metaphyseal bone (Fig. 77).
Figure 77. Varied radiographic appearance of osteosarcoma Lesions may be destructive (red arrow), osteogenic (yellow arrow), cause a moth-eaten appearance (orange arrow), or show combined osteoblastic and lytic features (white arrow).
Bone scans are helpful in identifying other affected sites. CT and MRI are helpful in assessing the osseous and soft tissue components of the lesion and in staging the tumor (Fig. 78). The histology (Fig. 79) shows tumor cells with primitive bone matrix formation.
Figure 78. Osteogenic sarcoma of the pelvis Note that the lesion is not readily identified on conventional radiographs (red arrow), but it is well imaged by bone scan (white arrow), CT (orange arrow), and MRI (yellow arrow).
Figure 79. Pathology of osteosarcoma This photomicrograph (left) shows tumor cell and primitive bone matrix formation. The gross specimen of the proximal humerus from an adolescent (right) shows the intramedullary tumor (yellow arrow) and periosteal new bone formation (red arrow).
Variants Osteosarcoma has several types with prognostic significance.
Parosteal osteosarcoma These well-differentiated lesions develop on the surface of the bone, such as the posterior femoral metaphysis, with little or no medullary involvement. Manage by wide local resection.
Periosteal osteosarcoma develops on long tubular bones, especially the tibia and femur. In contrast to parosteal osteosarcoma, periosteal osteosarcoma is less differentiated, resulting in a poorer prognosis.
Ewing Sarcoma
Ewing sarcoma is the second most common childhood malignant bone tumor.
Diagnosis The tumor is most common in the second decade (Fig. 80) and occurs most commonly in the pelvis, femur, and tibia (Fig. 81).
Figure 80. Ewing sarcoma Common (red) and less common (gray) locations are shown. The age of onset is shown in blue.
Figure 81. Typical radiographic features of Ewing sarcoma Note the diaphyseal location with periosteal reaction.
These tumors cause pain and sometimes present with a soft tissue mass. The lesion is usually diaphyseal (Fig. 82) and osteolytic or permeative in character.
Figure 82. Appearance of Ewing sarcoma Note the diaphyseal location (red arrow), the positive bone scan (yellow arrow), and extensive soft tissue involvement (blue arrow).
Bone scans and MRI are useful. Because the tumor may cause fever, leukocytosis, anemia, and an elevated sedimentation rate, it can be confused with osteomyelitis. Confirm the diagnosis by biopsy. This is a very malignant round cell tumor (Fig. 83).
Figure 83. Pathology of Ewing sarcoma This photomicrograph (left) shows small round cell tumor cells. Note the cortical destruction and extracortical extension in the proximal femur (right, arrow).
Management Management principles are similar for both osteosarcoma and Ewing sarcoma (Fig. 84). In general, Ewing sarcoma is primarily managed by chemotherapy and resection and often adjunctive radiation therapy
Figure 84. Management scheme Management of typical cases of osteosarcoma and Ewing sarcoma are shown
Chemotherapy Chemotherapeutic agents (Fig. 85) are commonly used in regimens of 3 to 5 agents given over a period of about 9 to 12 months, Typically, a third is administered preoperatively for a period of 4 to 6 weeks and the rest following resection for an additional 6 to 9 months.
Figure 85. Chemotherapeutic agents These agents are used together in various regimens for treating malignant tumors in children
Operative options Make the choice based on a discussion with the patient and family. Outcomes for various procedures are often comparable, and the choice is often best made based on the features of the tumor. Limb-sparing procedures have the greatest appeal to the child and family and have become the standard of care for most patients (Fig. 86).
Figure 86. Limb-sparing options Consider these options for limb salvage
Amputation versus limb-sparing procedures Each method has its indications and contraindications (Fig. 87). Functional outcomes are about the same. Patients managed by amputation have slightly lower functional scores but experience fewer complications from the surgery (Fig. 88).
Figure 87. Relative contraindications for limb salvage Consider management by limb ablation when these features are present. Based on DiCaprio MR and Friedlaender GE, JAAOS 11:25, 2003.
Figure 88. Comparison of outcomes of amputation and limb sparing procedures Note that the outcomes are similar.
Endoprosthesis Modular prosthetic management is gaining favor with time. Modern prostheses are strong, lightweight, and nonreactive (Fig. 89).
Figure 89. Endoprostheses Shown are replacements for the proximal humerus (yellow arrow) and distal femur (white arrow). The proximal tibial osteosarcoma (red arrow) resection was managed by a proximal tibial endoprosthesis (green arrow).
Rehabilitation can commence immediately, and acceptance is good. Infection and loosening are major problems. Problems with tendon and ligament attachments can occur. Replacements about the knee, especially the proximal tibia, are most problematic and demonstrate the highest failure rates. Between 30% and 40% require revisions within the first decade following replacement. Most infections and loosening problems can be resolved by revisions.
Expandable endoprosthesis For children, provide an option to maintain equal limb lengths. Design allows 6-9 cm with 1.5–2 cm expansion by minimally invasive procedures. Design improvements allow greater excursion and stable design.
Allografts Allografts may be intercalary, osteoarticular, or composites, combined with an endoprosthesis. Nonunion is the most common problem (Fig. 90). The allografts never completely incorporate, but they stabilize with time.
Figure 90. Allograft This intercallary allograft shows a nonunion (arrow) at its proximal junction.
This provides improved long-term function, making this a good choice for young people with long-bone diaphyseal tumors. In addition, attachments of tendons and ligaments are more satisfactory than with endoprostheses. Although intercallary allografts have the best results, osteoarticular reconstructions may be considered, especially about the knee. Because of tendon-ligament attachment capability, use around the knee has advantages over endoprostheses. Allograft outcomes may be improved by tissue typing in the future.
Rotationplasty This option provides the most energy-efficient outcome, best suited for children under 10 years of age with extensive tumors. Complications are few, and outcome allows a prosthetic fitting that is durable and functional. Most children function in sports. The major drawback is the complexity of the reconstruction and the appearance of the reconstructed limb. Preoperative meetings with other patients who have had the procedure are recommended. Although not in vogue, some suggest the procedure is better suited for boys than girls.
Other alternatives These include vascularized grafts, bone transport for lengthening, and arthrodesis. These options are less commonly considered, but may have a role for specific needs.
Management of malignant tumors is difficult, as the disease is potentially lethal. The options are numerous, making it necessary to integrate management and tailor management to the unique features of each child.
Leukemia
About 20% of children with leukemia present with bone pain and may first be seen by an orthopedist or rheumatologist. Common findings include bone pain, joint pain and swelling, antalgic gait, mild lymphadenopathy and hepatosplenomegaly, and a moderate fever. Radiographic findings include diffuse osteopenia, metaphyseal bands, periosteal new bone formation (Fig. 91), sclerosis, and a combination of sclerosis and lytic features. Usual laboratory findings include an elevated ESR, thrombocytopenia, anemia, decreased neutrophils, increased lymphocytes, and blast cells on the peripheral blood smear. Confirm the diagnosis with a bone marrow biopsy.
Figure 91. Leukemia Note the periosteal bone of the proximal ulna (arrow).
Metastatic Bone Tumors
The most common primary tumors are neuroblastoma followed by rhabdomyosarcoma (Fig. 92).
Figure 92. Tumors producing skeletal metastasis From data of Leeson et al. (1985).
Metastatic tumors to bone are most likely to involve the axial skeleton (Fig. 93).
Figure 93. Site and frequency of skeletal metastasis From data of Leeson et al. (1985).
Vertebrae metastases are most common in the lumbar spine, whereas thoracic and cervical involvements are less common. The primary site of tumors with spinal involvement are neuroblastoma and astrocytoma, depending on the patient’s age. Complications of spinal metastasis include paralysis, pathologic fractures, and kyphoscoliosis. Assess children with neuroblastoma and Ewing sarcoma for bony metastatic disease by CT, MRI, scintigraphy, or bone marrow biopsy. Extensive bony involvement is a relatively late finding (Fig. 94).
Figure 94. Metastatic neuroblastoma Note the extensive metatases in the pelvis and proximal femora.
