10. Pathology and Oncology MCQs

DISCUSSION: This is a nonossifying fibroma of the proximal tibia. The lesion is eccentric, cortically based, with sclerotic margins and no evidence of a soft-tissue mass. Nonossifying fibromas are benign lesions that need no biopsy or surgical treatment when classic findings appear on radiographs. A follow-up radiograph should be performed 2 to 3 months after the initial presentation to ensure that the lesion is not progressive. Surgery is reserved for large lesions with risk of pathologic fracture or for cases where a displaced pathologic fracture has occurred and internal fixation is needed for fracture treatment. Nondisplaced pathologic fractures through nonossifying fibromas are best treated by allowing the fracture to heal and observation of the lesion.

DISCUSSION: Soft-tissue sarcomas most frequently metastasize to the lung, but certain histologic types have a predilection for the lymph node system as well. Rhabdomyosarcoma, clear cell sarcoma, epithelioid sarcoma, and synovial sarcoma are four of the most common types to spread in this fashion. Careful evaluation and/or sentinel lymph node biopsy plays a role in disease staging and prognosis.

DISCUSSION: The images show a lobulated, eccentric, well-marginated lesion that is typical of a nonossifying fibroma. The lesion is slightly expansile, and the CT scan findings show that the lesion is very well marginated and the cortex is disrupted, which is a common finding. None of the characteristics of this lesion is aggressive in nature. REFERENCES: Menendez LR (ed): Orthopaedic Knowledge Update: Musculoskeletal Tumors. Rosemont, IL, American Academy of Orthopaedic Surgeons, 2002, pp 69-75. Parsons TW: Benign bone tumors, in Fitzgerald R Jr, Kaufer H, Malkani A (eds): Orthopaedics. Philadelphia, PA, Mosby International, 2002, pp 1027-1035.

DISCUSSION: In a young person with solitary osteochondroma, the best surgical indication is symptoms that limit activity. A growth deformity is unlikely to occur at this age. Malignant degeneration is exceptionally rare and noted most commonly in adults. Growth is expected until skeletal maturity. REFERENCES: Mirra JM: Bone Tumors: Clinical, Radiologic, and Pathologic Correlations. Philadelphia, PA, Lea and Febiger, 1989, pp 1626-1659. Simon MA, Springfield DS, et al: Common Benign Bone Tumors and Usual Treatment: Surgery for Bone and Soft Tissue Tumors. Philadelphia, PA, Lippincott Raven, 1998, pp 181-205.

DISCUSSION: Schwannomas (neurilemomas) occur at all ages but are most frequently seen in persons between the ages of 20 and 50 years. MRI features of schwannomas are fairly nonspecific, but when they are associated with a large named nerve, the identification of a mass in continuity with that nerve is highly suggestive of a schwannoma. Most have a fairly homogeneous appearance with a high water content and often fusiform shape. Classically, the histology shows alternating Antoni A (dense spindle cell region) areas and Antoni B (loose myxoid tissue) areas. They also demonstrate uniform intense immunostaining with S-100 protein. REFERENCES: Damron TA, Sim FH: Soft-tissue tumors about the knee. J Am Acad Orthop Surg 1997;5:141-152. Weiss SW, Goldblum JR, Enzinger FM: Enzinger and Weiss’s Soft Tissue Tumors, ed 4. Philadelphia, PA, Elsevier, 2001, pp 1146-1167.

While most pathologic fractures are in the lower extremity in patients treated for soft-tissue sarcomas by wide excision and adjuvant radiation therapy, risk factors for such fractures are bone resection associated with excision of the tumor and soft-tissue sarcomas of the thigh that require periosteal stripping at the time of resection. Such fractures can occur late, often more than 6 months after surgery, are difficult to treat, and often result in nonunion.

DISCUSSION: Pain secondary to an osteochondroma is usually from soft-tissue irritation and bursal formation. This is particularly common for proximal medial tibia osteochondromas that irritate the pes anserine tendons. Malignant degeneration into a chondrosarcoma rarely occurs, is usually associated with multiple hereditary exostoses, and usually occurs after skeletal maturity.

DISCUSSION: The radiograph shows a pathologic fracture through a destructive lesion of the distal femur metaphysis with osteolytic and osteoblastic features. The lateral cortex is destroyed, and there is periosteal new bone formation. These findings are consistent with malignancy, most likely an osteogenic sarcoma. Patients with suspected malignant tumors are best managed by surgeons with specific expertise in orthopaedic oncology. The biopsy of a malignant lesion should be deferred to the surgeon who is capable of definitive management of the patient.

Here is an algorithm from OKU 6 Tumors of the Spine pp 723-736This question gives you the history, skips right over physical exam and goes into plain films. With this patient’s history of hemoptysis and dyspnea and a lung mass, the next steps in this patients work-up would include the competion of initial work-up, metastatic work-up, then pre-operative planning. Goals of treatment are to 1) protect or restore neurologic function, 2) control pain,

DISCUSSION: The diagnosis is squamous cell carcinoma. The radiograph shows a destructive lesion, and the histologic slides demonstrate squamous cells invading bone. The preferred treatment for squamous cell carcinoma is wide resection; however, in this location a wide margin can be achieved only with amputation. Overall survival in patients with squamous cell carcinoma secondary to chronic osteomyelitis is not significantly worse than that expected for age-matched controls.

The patient has Langerhans cell histiocytosis that may be solitary (eosinophilic granuloma) or associated with systemic illness (Hand-Schuller-Christian disease and Letterer-Siwe disease). The solitary form of the disease, eosinophilic granuloma, typically affects patients in the first three decades of life. Radiographically, it is characterized as a well-defined, lytic, “punched out” intramedullary lesion. Histologically, two cell types, eosinophils and Langerhans cells, are seen. The Langerhans cells are seen as mononuclear histiocyte-like cells with oval nuclei with well-defined round or oval cytoplasm. A prominent nuclear groove can be seen in most of the nuclei (coffee bean nuclei). A mixture of inflammatory cells and lipid-laden foam cells with nuclear debris may be present as well. The lack of nuclear atypia and atypical mitoses excludes malignant conditions such as Ewing’s sarcoma, lymphoma of bone, and metastatic neuroblastoma. The lack of acute inflammatory cells excludes the diagnosis of osteomyelitis. The eosinophils have bi-lobed nuclei and granular eosinophilic cytoplasm.

DISCUSSION: In general, soft-tissue metastases to regional nodes are a relatively rare occurrence (less than 5% overall). The incidence of lymphatic metastasis is highest for synovial sarcoma, rhabdomyosarcoma, clear cell sarcoma, and epithelioid sarcoma. Regional nodes should be assessed clinically. CT is not used to routinely assess regional nodes. Evaluation of a sentinel node is not indicated because of the low incidence of regional nodal involvement. Fine needle aspiration may be indicated to assess clinically suspicious nodes. Prophylactic inguinal node dissection is contraindicated because it may lead to unnecessary complications such as lymphedema. REFERENCE: Sim FH, Frassica FJ, Frassica DA: Soft-tissue tumors: Diagnosis, evaluation and management. J Am Acad Orthop Surg 1994;2:202-211.

This is a classic appearance for an osteosarcoma. The radiographs reveal a mixed osteolytic and osteoblastic lesion in a skeletally immature patient in the distal right femoral metaphysis. The pain pattern with progressive symptoms leading to the presence of night pain is also typical for this condition. The biopsy specimen reveals pleomorphic cells and the presence of osteoid. The current standard of care in the treatment of osteosarcoma is neoadjuvant chemotherapy followed by surgical resection or amputation followed by additional postoperative chemotherapy. Osteosarcoma is not radiosensitive.

DISCUSSION: Although the imaging studies are consistent with a unicameral bone cyst, aneurysmal bone cyst, or giant cell tumor, the histology shows small round blue cells that are typical of Ewing’s sarcoma. Although Ewing’s sarcoma frequently occurs in the diaphysis, it can occur in the metaphysis. REFERENCE: Mirra J: Bone Tumors: Clinical, Radiologic, and Pathologic Correlations. Philadelphia, PA, Lea & Febiger, 1989, vol 2, ch 18.

DISCUSSION: The imaging studies are consistent with a chondrosarcoma. The radiograph shows a radiolucent lesion in the pelvis, and there are stippled calcifications on the CT scan. The histology shows a low-grade cellular hyaline cartilage neoplasm with stellate, occasionally binucleated chondrocytes. Enchondroma has a more benign histologic appearance. REFERENCE: Mirra JM, Gold R, Downs J, Eckardt JJ: A new histologic approach to the differentiation of enchondroma and chondrosarcoma of the bones: A clinicopathologic analysis of 51 cases. Clin Orthop 1985;201:214-237.

DISCUSSION: The most common location of osteosarcoma is the knee area (50% to 55%), followed by the proximal humerus and iliac wing. The most commonly involved long bone is the femur (40% to 45%), followed by the tibia (15% to 25%). Within these bones, tumors are typically adjacent to the epiphyses in most patients. The flat bones of the pelvis and spine are less frequently involved. REFERENCES: Malawer MM, Sugarbaker PH, Malawer M: Musculoskeletal Cancer Surgery: Treatment of Sarcomas and Allied Diseases. Kluwer Academic Publishers, 2001. Wold LA, et al: Osteogenic Sarcoma: Atlas of Orthopedic Pathology. Philadelphia, PA, WB Saunders, 1990, pp 14-15.

DISCUSSION: Synovial sarcomas have a number of features that differentiate them from other soft-tissue sarcomas. They often have small areas of calcifications within the lesion. They occur in a younger patient population than most soft-tissue sarcomas. A subset of patients with synovial sarcoma tend to be chemosensitive. They often contain the SYT-SSX translocation. Although they can occur intra-articular, this is rare, despite their name. REFERENCES: Campanacci M: Bone and Soft Tissue Tumors, ed 2. New York, NY, Springer-Verlag, 1999, pp 1109-1126. Simon SR (ed): Orthopaedic Basic Science. Rosemont, IL, American Academy of Orthopaedic Surgeons, 1994, pp 219-276.

The diagnosis is myositis ossificans resulting from an injury. The initial radiograph reveals a small amount of mineralization in the soft tissues overlying the left hip. The MRI scan shows signal abnormality of the entire gluteus minimus muscle with a mineralized mass in the center. The current radiograph shows a lesion within the abductor musculature with mature ossification peripherally. The imaging studies are diagnostic and the patient is asymptomatic; therefore, the management of choice is observation with no further evaluation or treatment indicated.

Soft-tissue sarcomas are the sixth most common cancer in children. Rhabdomyosarcoma is the most common type of pediatric soft-tissue sarcoma. Nearly 50% of rhabdomyosarcomas are diagnosed in children who are age 5 years or younger.