10. Pathology and Oncology MCQs

DISCUSSION: Osteoblastomas are benign lesions that represent less than 5% of benign bone tumors. Most lesions are located in the spine, followed by the femur, tibia, and skull. Patients with spinal lesions usually have pain that may be associated with scoliosis. The most common location in the spine is within the posterior elements.

DISCUSSION: The eccentric metaphyseal location, skeletal maturity, narrow zone of transition, and lack of symptoms suggest a benign process and are consistent with a healed nonossifying fibroma. These lesions typically fill in (ossify) with skeletal maturity, eventually remodeling and disappearing. Radiographic monitoring is indicated. Biopsy is not recommended unless the lesion changes radiographically. REFERENCES: Marks KE, Bauer TW: Fibrous tumors of bone. Orthop Clin North Am 1989;20:377-393. Bullough PG, Walley J: Fibrous cortical defect and non-ossifying fibroma. Postgrad Med J 1965;41:672-676. Skrede O: Non-osteogenic fibroma of bone. Acta Orthop Scand 1970;41:362-380.

DISCUSSION: The radiographic findings are classic for tumoral calcinosis; they are not consistent with myositis ossificans, fungal granuloma, or hemochromatosis. The condition typically appears as large aggregations of dense calcified lobules confined to the surrounding soft tissues. Hyperphosphatemia is a fundamental factor in many patients with this condition. Tumoral calcinosis also occurs in the setting of chronic renal failure when mineral homeostasis is not controlled. The histologic appearance is essentially a foreign body granuloma reaction. Surgical excision is indicated if the tumor causes discomfort or interferes with function.

Giant Cell tumors (GCT) are relatively common in the appendicular skeleton, most common during the 4th or 5th decades of life. GCT’s are destructive lesions with variable amounts of reactive bone at their margin. Successful treatment requires complete surgical excision.

DISCUSSION: The histology shows extraskeletal myxoid chondrosarcoma, characterized by abundant blue myxoid matrix with cords and nests of small tumor cells. Treatment consists of wide resection. Despite the name, hyaline cartilage is not a common component of these tumors. Adult rhabdomyosarcoma and malignant fibrous histiocytoma are highly pleomorphic sarcomas often containing multinucleated giant cells. Myxoid liposarcoma contains a prominent capillary network and lipoblasts. Myxoma is less cellular than extraskeletal myxoid chondrosarcoma and does not have a cord-like arrangement of tumor cells. REFERENCE: Kawaguchi S, Wada T, Nagoya S, Ikeda T, Isu K, Yamashiro K, et al: Extraskeletal myxoid chondrosarcoma. Cancer 2003;97:1285-1292.

DISCUSSION: The radiograph and histology findings are most consistent with squamous cell carcinoma. This tumor is best treated with wide surgical resection margins alone in the absence of metastasis; in this patient, management should consist of amputation through the distal interphalangeal joint. The other treatments are not indicated.

DISCUSSION: The factors that are independently prognostic of patient survival are tumor size, tumor grade, and tumor depth (ie, subfascial versus superficial). These factors are the basis for the American Joint Committee on Cancer staging criteria. Patient age and neurovascular invasion are not prognostic. Surgical margin is prognostic for local recurrence but not conclusively for patient survival or metastasis. Metastatic disease is also predictive of survival.

Rhabdomyosarcoma is a high grade malignancy with a rapid growth pattern. Local recurrence and distant metastasis after inadequate excision occurs in almost all instances and is uniformly fatal. The primary site of metastasis is the lung. Lymph node metastasis occurs in about > 10% of the patients, (synovial cell sarcoma = 25%). Whereas M.F.H. only occasionally metastasizes to regional LN, and liposarcoma is slow growing & recurrences or local metastasis is < 10%.

DISCUSSION: Multidisciplinary treatment combining systemic chemotherapy and adequate surgical resection has resulted in a 5-year survival rate of 70% in patients with nonmetastatic osteosarcoma of the extremity. The advent of effective chemotherapy has increased the overall survival rate from 20% to 70% in current studies.

DISCUSSION: The patient’s history, including the timing and type of symptoms, is typical for postoperative diskitis. The elevated ESR, 5 weeks after surgery, is also consistent with infection; a normal WBC count is not unusual. Management should consist of MRI with gadolinium; if positive, this should be followed by percutaneous biopsy to confirm the organism. Open biopsy may be considered if the percutaneous biopsy is unsuccessful. Anterior debridement and interbody fusion is reserved for the occasional patient that fails to respond to intravenous antibiotics, bed rest, and immobilization.

DISCUSSION: The patient has osteofibrous dysplasia. The radiographic differential diagnosis includes osteofibrous dysplasia, fibrous dysplasia, and adamantinoma. Histology shows a fibro-osseous lesion with prominent osteoblastic rimming but a lack of epithelial nests. Adamantinoma is a low-grade malignancy that typically is located in the anterior tibial cortex and has a soap bubble appearance. Histologically, it is similar to osteofibrous dysplasia but includes epithelial nests of cells. Treatment requires resection. Fibrous dysplasia usually does not require biopsy; however, in this patient the radiographs do not distinguish it from adamantinoma. The radiographic findings are not typical of Ewing’s sarcoma or osteosarcoma.

DISCUSSION: The most common location for soft-tissue tumors to metastasize is the lungs. Depending on the grade of the sarcoma, metastases develop in as many as 50% of patients with soft-tissue sarcomas. Tumor grade is considered the most significant prognostic factor in predicting risk of metastases, with high-grade lesions at greatest risk. Staging CT of the chest should be performed once the diagnosis of a soft-tissue sarcoma is suspected or confirmed.

DISCUSSION: The greatest risk factor for local recurrence is an inadequate surgical margin. The tumor grade, histologic subtype, and size are predictive of systemic relapse. Sarcomas that arise in some anatomic sites, such as the forearm or retroperitoneum, may be more difficult to completely resect compared with other sites. The optimum margin is generally considered to be a cuff of normal tissue beyond the tumor.

DISCUSSION: The most likely diagnosis is postpolio syndrome, which is characterized by increasing weakness in both the paretic and previously normal muscles. Fatigability, joint pain, muscle atrophy, respiratory insufficiency, dysphagia, and sleep apnea are also seen. Gentle exercise and modification in lifestyle demands are generally recommended. Vigorous rehabilitation is likely to be detrimental in this condition. Further diagnostic work-up is not indicated at this time.

DISCUSSION: Ewing’s sarcoma has an 11;22 translocation that creates the EWS/FLI1 fusion gene, and synovial sarcoma has an X;18 translocation that creates the SYT/SSX fusion gene. The other tumors do not have consistent translocations. REFERENCES: Sandberg AA: Cytogenetics and molecular genetics of bone and soft-tissue tumors. Am J Med Genet 2002;115:189-193. Menendez LR (ed): Orthopaedic Knowledge Update: Musculoskeletal Tumors. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2002, pp 11-20.

DISCUSSION: A destructive mixed lytic and blastic metaphyseal lesion with a large soft-tissue mass in an adolescent is most likely an osteosarcoma until proven otherwise. The epicenter of the tumor is on the surface of the bone, most likely involves the periosteum, and is more likely to be chondroblastic in nature. Parosteal osteosarcoma is a low-grade tumor, much more radiodense, usually smaller, and found in the posterior distal femur of middle-aged patients. Chondrosarcomas are distinctly rare in childhood. REFERENCE: Bertoni F, Bacchini P: Classification of bone tumors. Eur J Radiol 1998;27:S74-S76.

DISCUSSION: The patient underwent a wide resection, which involves excision of the tumor along with a cuff of normal tissue that completely surrounds the tumor. The plane of resection is beyond the reactive zone. A radical resection involves removal of the entire affected muscle from origin to insertion. In a marginal excision, the plane of dissection is through the reactive zone of the tumor. A marginal excision is generally considered inadequate surgery for high-grade sarcomas. In an intralesional resection, the plane of dissection is through the tumor. Excision within the reactive zone but beyond the tumor is the same as a marginal excision. REFERENCES: Enneking WF: Staging of musculoskeletal neoplasms, in Current Concepts of Diagnosis and Treatment of Bone and Soft Tissue Tumors. Heidelberg, Germany, Springer-Verlag, 1984. Simon MA, Springfield D: Surgery for Bone and Soft Tissue Tumors. Philadelphia, PA, Lippincott-Raven, 1998.

DISCUSSION: Following excision of a suspected benign soft-tissue tumor that proves to be malignant, repeat excision of the tumor bed is recommended. The initial surgical margins are inadequate after an intralesional or marginal excision, necessitating additional surgery for more definitive local control. While radiation therapy and/or chemotherapy may help to reduce the risk of local recurrence in patients with microscopic residual disease, local control is improved following repeat excision. Radiation therapy alone is inadequate to address poor surgical margins, and would likely be given postoperatively. Bisphosphonates have no current role in the treatment of soft-tissue sarcoma. REFERENCES: Noria S, Davis A, Kandel R, et al: Residual disease following unplanned excision of soft-tissue sarcoma of an extremity. J Bone Joint Surg Am 1996;78:650-655. Bell RS, O’Sullivan B, Liu FF, et al: The surgical margin in soft-tissue sarcoma. J Bone Joint Surg Am 1989;71:370-375.