10. Pathology and Oncology MCQs

A 25-year-old male presents with a long-standing history of anterior leg pain. Radiographs reveal an eccentrically located, multi-loculated, purely lytic lesion in the anterior tibial diaphysis. Biopsy demonstrates a biphasic tumor with nests of epithelial cells surrounded by a fibrous stroma. Immunohistochemistry is strongly positive for cytokeratin.

What is the most likely diagnosis?

A 45-year-old woman presents with progressive diffuse muscle weakness and bone pain over the past year. Laboratory studies reveal severe hypophosphatemia, normocalcemia, normal PTH levels, and markedly elevated alkaline phosphatase. Further workup identifies a small soft tissue mass in her thigh. Secretion of which of the following substances by this tumor is primarily responsible for her metabolic derangement?

A 28-year-old male presents with a slowly enlarging soft tissue mass near his knee joint. MRI shows a heterogenous, well-circumscribed juxta-articular soft tissue mass that does not enter the joint space. Biopsy confirms a biphasic morphology with spindle cells and epithelial-like glandular structures.

Which specific chromosomal translocation is diagnostic for this malignancy?

A 55-year-old male presents with bowel and bladder dysfunction and sacral pain. Imaging demonstrates a destructive midline sacral mass. Core needle biopsy reveals large, vacuolated cells with abundant bubbly cytoplasm arranged in cords and lobules within a myxoid stroma. Which of the following immunohistochemical markers is most highly sensitive and specific for confirming this diagnosis?

A 16-year-old boy presents with severe right thigh pain that awakens him from sleep. The pain is consistently and rapidly relieved by taking ibuprofen. A CT scan demonstrates a well-circumscribed 8 mm radiolucent nidus surrounded by dense sclerotic bone in the proximal femur. The intense, nocturnal pain experienced by this patient is directly mediated by dramatically elevated local production of which of the following?

A slow-growing primary malignant bone tumor composed of abundant clear cytoplasm and chondroid matrix is diagnosed on core needle biopsy. Which of the following best describes the typical demographic and anatomical location for Clear Cell Chondrosarcoma?

A 55-year-old male presents with deep thigh pain. Radiographs show a permeative, destructive diaphyseal lesion in the femur with minimal periosteal reaction. MRI shows extensive marrow replacement. Biopsy yields a diagnosis of primary lymphoma of bone.

The majority of primary bone lymphomas will stain strongly positive for which of the following cluster of differentiation (CD) markers?

A 22-year-old male presents with a painful mass in his quadriceps muscle 4 weeks after suffering a blunt contusion during a football game. A biopsy is taken from the mass due to concerns for a soft tissue sarcoma. Which of the following histologic patterns is most characteristic of Myositis Ossificans and helps distinguish it from an extraskeletal osteosarcoma?

A 35-year-old female presents with a painless mass on the posterior aspect of her distal thigh. Radiographs demonstrate a dense, lobulated, heavily ossified mass attached to the posterior cortex of the distal femur on a broad stalk, with no medullary involvement. A core biopsy confirms a low-grade malignant spindle cell stroma with well-formed woven bone trabeculae. Amplification of which of the following gene pairs is a pathognomonic molecular feature of this tumor?

A 65-year-old male with a known history of metastatic clear cell Renal Cell Carcinoma (RCC) presents with an impending pathologic fracture of his right proximal femur.

A prophylactic stabilization surgery is planned. Which of the following preoperative interventions is most critical to reduce perioperative mortality and morbidity?

Aneurysmal bone cysts (ABCs) were historically considered entirely reactive lesions but are now recognized to have a primary neoplastic pathogenesis in many cases. Primary ABCs are most commonly driven by a recurrent chromosomal translocation resulting in the upregulation of which of the following genes?

A 14-year-old girl is evaluated for a progressive deformity of her proximal femur. Radiographs show a purely lytic lesion in the metadiaphysis with a classic 'ground-glass' matrix and a 'shepherd's crook' varus deformity.

Which of the following genetic alterations is responsible for the pathogenesis of this condition?

A 21-year-old male presents with chronic, dull back pain. Radiographs and CT show a 3.5 cm expansile, radiolucent mass with central ossification involving the posterior elements of the L4 vertebra.

Which of the following features differentiates this diagnosis (Osteoblastoma) from an Osteoid Osteoma?

A 28-year-old female presents with a deep-seated soft tissue mass in her foot. A biopsy is obtained and demonstrates nests of pale spindle cells separated by fibrous septae. The tumor stains positive for S-100 and HMB-45.

This lesion, historically known as 'melanoma of soft parts,' is characterized by which of the following cytogenetic abnormalities?

A 28-year-old female presents with a painless mass on the posterior aspect of her distal thigh. Radiographs demonstrate a dense, lobulated, ossified mass attached to the posterior cortex of the distal femur by a broad base, with a visible radiolucent 'string sign' separating part of the tumor from the cortex. Histologic examination reveals well-differentiated spindle cells with minimal atypia embedded in a fibrous stroma, interspersed with well-formed woven bone trabeculae.

Which of the following genetic amplifications is diagnostic for this condition?

A 14-year-old boy presents with multiple unilateral cartilaginous bone tumors and multiple soft tissue hemangiomas exhibiting phleboliths on radiographs. He is diagnosed with a rare non-hereditary congenital disorder. What is the most likely gene mutation associated with this syndrome?

A 45-year-old male presents with chronic hip pain. Radiographs reveal a secondary well-defined, slightly expansile lytic lesion in the epiphysis of the proximal femur. Biopsy reveals uniform cells with central nuclei and abundant vacuolated clear cytoplasm, distinctly clear cell borders, scattered multinucleated giant cells, and reactive bone formation. Which of the following is the most likely diagnosis?

A 35-year-old female undergoes targeted medical therapy for a recurrent, diffuse, destructive intra-articular mass in her knee that is no longer amenable to surgical resection. Histology previously confirmed Pigmented Villonodular Synovitis (PVNS), also known as Tenosynovial Giant Cell Tumor.

What is the primary molecular target of the FDA-approved systemic therapy (e.g., Pexidartinib) for this condition?

A 25-year-old male presents with anterior lower leg pain. Radiographs show a well-circumscribed, multiloculated, expansile osteolytic lesion in the anterior diaphysis of the tibia. A biopsy demonstrates a biphasic pattern consisting of epithelial cells forming nests and tubular structures, surrounded by bland fibrous spindle cells. The epithelial cells stain strongly positive for cytokeratin. What is the recommended surgical management for this pathology?