10. Pathology and Oncology MCQs

A 12-year-old boy presents with severe, aching pain in his mid-thigh that is significantly worse at night and dramatically relieved by ibuprofen. Radiographs show cortical thickening with a small radiolucent nidus. The symptomatic relief provided by NSAIDs is primarily due to the inhibition of which biochemical mediator produced by the tumor?

A 10-year-old girl presents with a large, destructive, permeative diaphyseal lesion of the femur with an 'onion-skin' periosteal reaction. A biopsy is performed. The diagnosis of Ewing sarcoma is supported by a strong, diffuse membranous staining for CD99. To further distinguish this from other small blue cell tumors, which of the following immunohistochemical markers is currently considered the most highly sensitive and specific adjunct?

A 30-year-old male presents with a slowly enlarging, deep-seated soft tissue mass in the thigh near the knee joint. Biopsy reveals a biphasic tumor comprised of both epithelial components (glandular structures) and a spindle cell mesenchymal stroma. Which of the following cytogenetic abnormalities is diagnostic for this tumor?

A 28-year-old female presents with a painless, hard mass on the posterior aspect of her distal thigh. Radiographs demonstrate a dense, lobulated, heavily ossified mass arising from the posterior cortex of the distal femur, with a thin radiolucent 'cleft' separating the bulk of the tumor from the underlying cortex. Biopsy reveals a low-grade fibroblastic stroma with parallel trabeculae of woven bone. Amplification of which gene is the molecular hallmark of this entity?

A 70-year-old man with advanced prostate cancer develops multiple dense, osteoblastic metastatic lesions in his lumbar spine and pelvis. The characteristic osteosclerotic nature of these metastatic bone lesions is primarily driven by tumor cell secretion of which of the following factors?

A 22-year-old male is evaluated for multiple bony deformities and is diagnosed with Ollier disease, characterized by multiple enchondromas. He is counseled regarding the risk of malignant transformation. Somatic mosaic mutations in which of the following genes are the primary driver for both Ollier disease and Maffucci syndrome?

A 16-year-old boy presents with a rapidly expanding, painful distal femoral lytic lesion. MRI reveals multiple fluid-fluid levels, mimicking an Aneurysmal Bone Cyst (ABC). A biopsy is performed to rule out Telangiectatic Osteosarcoma. Which of the following histologic features definitively establishes the diagnosis of Telangiectatic Osteosarcoma over an ABC?

A 5-year-old boy presents with a painless anterior bowing of his right tibia. Radiographs reveal a multilocular, intracortical radiolucent lesion of the anterior diaphyseal tibia. A biopsy is obtained to differentiate this from fibrous dysplasia. Which of the following histologic findings is characteristic of Osteofibrous Dysplasia and absent in classical Fibrous Dysplasia?

A 22-year-old male presents with chronic knee pain. Imaging reveals an eccentric, well-demarcated lytic lesion with a sclerotic rim in the proximal tibial metaphysis. Biopsy exhibits a distinct lobular architecture with a myxoid and chondroid background. The periphery of the lobules is highly cellular with spindle-shaped cells, whereas the center is hypocellular with stellate cells. What is the most likely diagnosis?

A 35-year-old woman presents with a locally aggressive, destructive radiolucent lesion in the mandibular ramus, extending into the soft tissues. Biopsy reveals a dense proliferation of uniform, elongated spindle cells producing abundant collagen without nuclear atypia, mitosis, or any osteoid or chondroid matrix formation. Molecular analysis demonstrates a mutation in the CTNNB1 gene. This lesion is the intraosseous counterpart to which of the following soft tissue tumors?

A 14-year-old boy presents with aching pain in his proximal tibia that is significantly worse at night and rapidly relieved by ibuprofen. Radiographs demonstrate a radiolucent nidus less than 1.5 cm surrounded by reactive sclerosis. Which biochemical mediator is produced in exceptionally high quantities by the cells within this nidus?

A 25-year-old female presents with a slow-growing, painless mass on the posterior aspect of her distal femur. Radiographs reveal a dense, heavily ossified mass attached to the cortex via a broad base with a 'string sign' indicating a radiolucent cleft. Genetic analysis of the tumor cells is most likely to reveal which of the following abnormalities?

A 30-year-old man presents with a slow-growing, deep-seated soft tissue mass in his foot. Biopsy reveals nests of pale-staining spindle cells separated by fibrous septa. Immunohistochemistry is strongly positive for HMB-45, Melan-A, and S-100. Which chromosomal translocation defines this neoplasm?

A 40-year-old male undergoes excision of a deep thigh mass. Histopathology shows a proliferation of uniform round cells, signet-ring lipoblasts, and a prominent branching capillary network resembling 'chicken wire' in a myxoid stroma. What is the characteristic genetic translocation associated with this sarcoma?

A 12-year-old boy presents with a 'shepherd's crook' deformity of his proximal femur. Radiographs demonstrate an expansive, intramedullary ground-glass lesion. What is the underlying cellular mechanism driving the pathogenesis of this osseous lesion?

A 28-year-old male presents with dull, aching anterior lower leg pain. Radiographs show a multicystic, eccentric, expansile lytic lesion in the anterior tibial diaphysis. Histopathology reveals islands and nests of epithelial cells surrounded by a bland fibrous stroma. Which immunohistochemical stain is most likely positive in the lesional cells?

A 55-year-old male presents with chronic constipation and saddle anesthesia. Imaging reveals a large, destructive midline sacral mass. Biopsy shows large, vacuolated cells arranged in lobules and cords within a prominent myxoid stroma. Which immunohistochemical marker is highly specific for confirming this diagnosis?

A 35-year-old female undergoes MRI for recurrent, unexplained bloody knee effusions. The imaging reveals a nodular synovial mass demonstrating low signal intensity on both T1 and T2 sequences, with a 'blooming' artifact on gradient echo. What is the primary pathogenic mechanism driving the growth of this mass?

A 68-year-old man presents with severe generalized back pain, normocytic anemia, and hypercalcemia. Radiographs show multiple punched-out lytic skull lesions. Which of the following imaging modalities is generally considered the LEAST sensitive for detecting the extent of skeletal involvement in this specific disease process?