10. Pathology and Oncology MCQs

A 15-year-old boy presents with a rapidly growing, deep soft tissue mass in his forearm. Biopsy reveals a dense proliferation of primitive small round blue cells. The cells are divided into discrete nests by fibrous septa, with central discohesion of cells creating spaces that mimic pulmonary alveoli. Which genetic fusion is most characteristic of this aggressive sarcoma?

A 30-year-old female presents with a painless, slow-growing mass on the posterior aspect of the distal femur. Radiographs reveal a dense, heavily ossified mass broadly attached to the posterior cortex. Notably, a thin radiolucent line ('string sign') separates a portion of the tumor from the underlying cortex.

Histologically, the lesion consists of low-grade spindle cells interspersed among parallel trabeculae of woven and lamellar bone. Which genetic abnormality is characteristic of this tumor?

A 35-year-old male presents with a painless, slowly enlarging swelling over his right shin. Radiographs reveal an eccentric, multi-loculated osteolytic lesion in the anterior cortex of the tibial diaphysis. Biopsy demonstrates a biphasic tumor with nests of epithelial cells surrounded by a bland fibrous stroma. Which of the following immunohistochemical markers is most characteristically positive in the neoplastic cellular nests of this lesion?

A 42-year-old male presents with persistent shoulder pain. Radiographs show a lytic lesion in the proximal humeral epiphysis. Histological examination reveals sheets of neoplastic cells with abundant clear cytoplasm, distinct cell membranes, scattered osteoclast-like multinucleated giant cells, and areas of chondroid matrix. What is the most likely diagnosis?

A 25-year-old male presents with a slow-growing soft tissue mass in the plantar aspect of his foot. Radiographs show a soft tissue density with focal stippled calcifications. Biopsy reveals a biphasic tumor consisting of spindle cells and glandular epithelial structures. Which of the following translocations is diagnostic for this tumor?

A 30-year-old female presents with recurrent, painful swelling of her knee. Joint aspiration yields brownish fluid. MRI reveals a thickened synovium with prominent blooming artifact on gradient-echo sequences. The pathogenesis of this condition is primarily driven by a t(1;2) translocation leading to the overexpression of which of the following?

A 62-year-old male presents with chronic constipation and lower back pain. Imaging reveals a large, destructive, midline mass in the sacrum. Biopsy demonstrates lobules of large cells with prominent intracytoplasmic vacuoles (physaliferous cells) in a myxoid background. Which immunohistochemical marker is highly sensitive and specific for distinguishing this tumor from chondrosarcoma?

A 32-year-old male presents with a slowly enlarging, ulcerated nodule on the volar aspect of his wrist. Initial biopsy was misinterpreted as a necrotizing granuloma. Re-evaluation reveals a proliferation of plump epithelioid cells surrounding central areas of necrosis. Immunohistochemistry shows loss of nuclear expression of INI1 (SMARCB1). What is the diagnosis?

A 16-year-old boy presents with mild, chronic knee pain. Radiographs demonstrate an eccentric, sharply circumscribed, well-demarcated osteolytic lesion with a sclerotic margin in the metaphysis of the proximal tibia. Histology shows a lobulated architecture with hypocellular centers containing stellate/spindle cells in a myxoid stroma, and hypercellular peripheries containing multinucleated osteoclast-like giant cells. What is the diagnosis?

A 15-year-old male undergoes curettage of a 3 cm lytic lesion located exclusively in the greater tuberosity epiphysis of the proximal humerus. Histological analysis reveals sheets of mononuclear cells with characteristic nuclear grooves, prominent eosinophilic cytoplasm, and focal areas of fine, intercellular pericellular calcifications. Molecular testing of this lesion is most likely to reveal a mutation in which of the following genes?

A 55-year-old male is referred for an asymptomatic calcified lesion discovered incidentally on a radiograph of his proximal humerus. The radiologist suggests distinguishing between an enchondroma and a low-grade (Grade 1) central chondrosarcoma. Which of the following MRI or radiographic findings is the most reliable indicator favoring a diagnosis of low-grade chondrosarcoma over enchondroma?

A 48-year-old female presents with generalized weakness, recurrent nephrolithiasis, and bilateral multi-focal lytic bone lesions. A biopsy of a femoral lesion demonstrates a highly vascularized stroma containing plump spindle cells, areas of hemorrhage, and clusters of osteoclast-like multinucleated giant cells. Which of the following laboratory profiles is most likely to be found in this patient?

A 22-year-old female presents with a slow-growing, painless mass deep in the vastus lateralis. Staging reveals multiple small brain metastases. Biopsy of the primary tumor shows large, polygonal cells with abundant granular eosinophilic cytoplasm arranged in a nested, pseudoalveolar pattern. PAS staining reveals diastase-resistant rhomboid crystals in the cytoplasm. What is the specific genetic alteration driving this tumor?

A 52-year-old male undergoes MRI for chronic lumbar radiculopathy. An incidental lesion is noted in the L3 vertebral body. Sagittal T1- and T2-weighted MRI both show high signal intensity in the lesion, and axial CT shows a "polka-dot" pattern of thickened trabeculae. What is the most appropriate management for this specific lesion?

A 6-year-old boy presents with painless anterolateral bowing of his left tibia. Radiographs show multiple anterior intracortical lytic lesions in the tibial diaphysis. Histology shows a fibroblastic stroma surrounding trabeculae of woven bone that are lined by a prominent layer of active osteoblasts. No epithelial cells are identified on extensive sectioning. This lesion has a known clinical association with, and must be carefully distinguished from, which of the following malignancies?

A 68-year-old male with a history of fatigue and normocytic anemia presents with severe, acute onset back pain. Radiographs reveal multiple 'punched-out' lytic lesions in his skull and a compression fracture of T10. Serum protein electrophoresis (SPEP) demonstrates an M-spike. If a biopsy of the skull lesion were performed, what would be the most prominent immunohistochemical finding?

A 32-year-old female presents with a slowly enlarging, hard mass on the posterior aspect of her distal femur. Plain radiographs display a heavily ossified, dense, lobulated mass arising from the cortex, with a radiolucent line (cleft) separating parts of the tumor from the underlying bone cortex. Histological examination shows bland, well-differentiated spindle cells arranged between parallel trabeculae of mature woven and lamellar bone. Molecular analysis is most likely to show amplification of which genomic region?

An 18-year-old female presents with a deep thigh mass. Biopsy reveals a primitive, small round cell tumor. Molecular analysis demonstrates a t(11;22)(q24;q12) translocation resulting in an EWSR1-FLI1 fusion transcript. Although this tumor typically arises in bone, when it presents as a primary soft tissue mass (extraskeletal), it must be differentiated from which morphologically identical tumor that belongs to the same family and shares the identical genetic driver?

A 15-year-old boy presents with knee pain and swelling. Radiographs reveal a lytic and blastic lesion in the distal femoral metaphysis with a 'sunburst' periosteal reaction. Biopsy demonstrates malignant cells producing osteoid matrix. Which of the following tumor suppressor genes are most frequently inactivated in the pathogenesis of this primary bone tumor?