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10. Pathology and Oncology MCQs

Practice Set 277 of 351

This practice set contains high-yield board review questions covering key concepts in 10. Pathology and Oncology. Each clinical scenario is designed to test your diagnostic and management skills relevant to this subspecialty.

Question 5521

Topic: 10. Pathology and Oncology

A 55-year-old man undergoes a biopsy of a destructive proximal humerus lesion that demonstrated endosteal scalloping and soft tissue extension on MRI. Histopathology demonstrates hypercellular cartilage with nuclear pleomorphism and binucleate cells in a myxoid stroma. Which of the following is the most appropriate definitive management for a Grade 2 lesion of this type?

. Neoadjuvant chemotherapy followed by intralesional curettage
. Definitive radiation therapy
. Intralesional curettage with adjuvant phenol and bone grafting
. Wide surgical resection
. Observation with serial radiographs

Correct Answer & Explanation

. Wide surgical resection

Explanation

The histopathology and clinical description are diagnostic of intermediate to high-grade (Grade 2 or 3) conventional chondrosarcoma. Unlike Grade 1 lesions, which can often be treated with extended intralesional curettage, Grade 2 and 3 chondrosarcomas require wide surgical resection. They are notoriously resistant to chemotherapy and radiation.

Question 5522

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with a diaphyseal mass in the femur. Radiographs reveal a permeative destructive lesion with an 'onion-skin' periosteal reaction. Genetic testing of the biopsy specimen is most likely to reveal which of the following chromosomal translocations?

. t(11;22)
. t(9;22)
. t(X;18)
. t(12;16)
. t(2;13)

Correct Answer & Explanation

. t(11;22)

Explanation

The clinical picture describes Ewing sarcoma, characterized classically by an 'onion-skin' (lamellated) periosteal reaction in the diaphysis of long bones. The hallmark genetic mutation is the t(11;22)(q24;q12) chromosomal translocation, resulting in the EWS-FLI1 fusion protein, found in approximately 85% of cases.

Question 5523

Topic: 10. Pathology and Oncology

A 15-year-old boy presents with right knee pain and swelling for two months. Radiographs demonstrate an aggressive, mixed lytic and blastic lesion in the distal femoral metaphysis with a 'sunburst' periosteal reaction.

A biopsy is performed. Which of the following histologic features is the sine qua non for the diagnosis of this patient's most likely condition?

. Small round blue cells with Homer-Wright rosettes
. A uniform population of plump, atypical chondrocytes in a myxoid stroma
. Malignant mesenchymal cells producing unmineralized osteoid
. Multinucleated giant cells in a background of mononuclear stromal cells
. Nests of epithelial cells in a dense fibrous stroma

Correct Answer & Explanation

. Malignant mesenchymal cells producing unmineralized osteoid

Explanation

The clinical presentation and radiographic features are classic for osteosarcoma. The defining histologic feature of osteosarcoma, distinguishing it from other primary bone tumors, is the production of osteoid (immature, unmineralized bone matrix) directly by malignant, neoplastic mesenchymal spindle cells. Homer-Wright rosettes indicate Ewing sarcoma, uniform atypical chondrocytes point to chondrosarcoma, and multinucleated giant cells suggest Giant Cell Tumor of bone.

Question 5524

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with a diaphyseal mass in his femur. Biopsy reveals small round blue cells. Molecular testing is expected to show an EWS-FLI1 fusion protein resulting from which of the following chromosomal translocations?

. t(11;22)
. t(9;22)
. t(X;18)
. t(2;13)
. t(12;16)

Correct Answer & Explanation

. t(11;22)

Explanation

Ewing sarcoma is characterized by the t(11;22) chromosomal translocation in approximately 85% of cases. This translocation results in the EWS-FLI1 fusion protein.

Question 5525

Topic: Bone Tumors

A 19-year-old male presents with night pain in his tibia that is dramatically relieved by NSAIDs. Radiographs show a small radiolucent nidus surrounded by dense sclerotic bone. The dramatic pain relief provided by NSAIDs is due to the inhibition of which molecule highly produced by this lesion?

. Interleukin-1 (IL-1)
. Tumor necrosis factor-alpha (TNF-a)
. Prostaglandin E2 (PGE2)
. Transforming growth factor-beta (TGF-b)
. Bone morphogenetic protein-2 (BMP-2)

Correct Answer & Explanation

. Prostaglandin E2 (PGE2)

Explanation

The typical presentation describes an osteoid osteoma. The nidus of an osteoid osteoma produces high levels of Prostaglandin E2 (PGE2), which causes the severe, localized night pain that is characteristically relieved by NSAIDs.

Question 5526

Topic: 10. Pathology and Oncology

A 60-year-old male presents with new-onset, severe thigh pain. Radiographs reveal a central, stippled calcified lesion in the proximal femur with an associated large, radiolucent, destructive soft-tissue mass extending beyond the cortex. Biopsy of the soft-tissue mass shows a high-grade spindle cell sarcoma. What is the most likely diagnosis?

. Osteosarcoma
. Dedifferentiated chondrosarcoma
. Ewing sarcoma
. Metastatic renal cell carcinoma
. Malignant fibrous histiocytoma

Correct Answer & Explanation

. Dedifferentiated chondrosarcoma

Explanation

The classic radiographic and histologic appearance of a dedifferentiated chondrosarcoma is a low-grade cartilaginous tumor (central calcifications) with an abrupt transition to a high-grade, non-chondroid sarcoma. The soft tissue component is typically a high-grade spindle cell sarcoma, such as osteosarcoma or undifferentiated pleomorphic sarcoma.

Question 5527

Topic: Bone Tumors

A 9-year-old boy presents with arm pain after throwing a baseball. Radiographs reveal a minimally displaced pathologic fracture through a centrally located, geographic, purely radiolucent lesion in the proximal humerus metaphysis. A small fragment of cortical bone is seen resting at the dependent portion of the radiolucent cavity.

What is the most likely diagnosis?

. Aneurysmal bone cyst
. Unicameral bone cyst
. Non-ossifying fibroma
. Eosinophilic granuloma
. Osteosarcoma

Correct Answer & Explanation

. Unicameral bone cyst

Explanation

The scenario describes the classic 'fallen leaf' (or 'fallen fragment') sign, which is pathognomonic for a unicameral bone cyst (UBC), also known as a simple bone cyst. It occurs when a piece of the thin cortical wall fractures and falls into the fluid-filled cavity. Aneurysmal bone cysts (ABCs) are typically eccentrically located and expansile, and do not demonstrate this sign.

Question 5528

Topic: 10. Pathology and Oncology

A 3-month-old infant presents with irritability, fever, and massive swelling of the mandible and bilateral clavicles. Radiographs reveal marked periosteal new bone formation. Laboratory studies show an elevated ESR and alkaline phosphatase. What is the most appropriate management?

. Urgent incision and drainage for osteomyelitis
. Excisional biopsy to rule out Ewing sarcoma
. Reassurance and administration of NSAIDs
. High-dose IV antibiotics for 6 weeks
. Methotrexate and TNF-alpha inhibitors

Correct Answer & Explanation

. Reassurance and administration of NSAIDs

Explanation

The clinical picture is classic for Infantile Cortical Hyperostosis (Caffey disease). It typically presents before 6 months of age with a triad of irritability, soft tissue swelling, and cortical thickening/hyperostosis of the underlying bones (most commonly the mandible, clavicles, and ulnae). It is a self-limiting inflammatory condition that resolves spontaneously, and treatment is symptomatic with NSAIDs.

Question 5529

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with a diaphyseal femur lesion showing an 'onion skin' periosteal reaction. A biopsy reveals small round blue cells. Which specific chromosomal translocation is most commonly associated with this pathology?

. t(11;22)(q24;q12)
. t(X;18)(p11;q11)
. t(12;16)(q13;p11)
. t(2;13)(q35;q14)
. t(9;22)(q34;q11)

Correct Answer & Explanation

. t(11;22)(q24;q12)

Explanation

Ewing sarcoma is classically characterized by the t(11;22)(q24;q12) translocation, resulting in the EWS-FLI1 fusion protein. t(X;18) is seen in synovial sarcoma. t(12;16) is seen in myxoid liposarcoma. t(2;13) is seen in alveolar rhabdomyosarcoma.

Question 5530

Topic: Bone Tumors
A 55-year-old male presents with deep thigh pain. Radiographs show a large destructive diaphyseal lesion with 'popcorn' calcification. Histology shows abundant hyaline cartilage with significant atypia. Which of the following is the mainstay of treatment for conventional Grade II chondrosarcoma?
. Neoadjuvant chemotherapy followed by wide surgical resection
. Definitive radiation therapy
. Wide surgical resection alone
. Curettage and cementation
. Primary amputation

Correct Answer & Explanation

. Wide surgical resection alone

Explanation

Conventional chondrosarcomas are notoriously resistant to both chemotherapy and radiation therapy due to their poor vascularity, extracellular matrix, and slow growth rate. The mainstay of treatment for intermediate to high-grade (Grade II or III) chondrosarcomas is wide surgical resection alone.

Question 5531

Topic: 10. Pathology and Oncology

A 15-year-old male presents with distal thigh pain. Radiographs show a destructive metaphyseal lesion with a 'sunburst' periosteal reaction. Before proceeding with a biopsy, what is the most critical next imaging step to plan definitive surgical management?

. MRI of the entire involved bone
. CT scan of the chest
. Technetium-99m bone scan
. Positron emission tomography (PET)
. CT scan of the affected extremity

Correct Answer & Explanation

. MRI of the entire involved bone

Explanation

MRI of the entire affected bone (whole extremity) must be obtained prior to biopsy to assess the intraosseous/extraosseous extent of the tumor and rule out skip lesions. This imaging is crucial for planning the biopsy tract and subsequent en bloc resection.

Question 5532

Topic: 10. Pathology and Oncology

Which of the following is the most common primary malignant bone tumor in adults over the age of 40?

. Osteosarcoma
. Chondrosarcoma
. Ewing sarcoma
. Multiple myeloma
. Malignant fibrous histiocytoma

Correct Answer & Explanation

. Multiple myeloma

Explanation

Multiple myeloma is the most common primary malignancy of bone overall and specifically in adults over 40. It is a hematologic malignancy characterized by plasma cell proliferation and lytic bone lesions.

Question 5533

Topic: Bone Tumors

A 65-year-old male presents with persistent mid-back pain, fatigue, and recent onset of polyuria. Laboratory tests reveal normocytic anemia and hypercalcemia. Radiographs show multiple punched-out lytic lesions in the vertebral bodies. Which of the following is the most appropriate initial diagnostic test to confirm the underlying pathology?

. Bone scintigraphy (Tc-99m)
. Serum alkaline phosphatase
. Serum and urine protein electrophoresis
. Dual-energy X-ray absorptiometry (DEXA)
. Positron emission tomography (PET)

Correct Answer & Explanation

. Serum and urine protein electrophoresis

Explanation

Serum and urine protein electrophoresis with immunofixation is the most appropriate initial diagnostic test for multiple myeloma. It detects the monoclonal protein spike (M-spike) characteristic of the disease. Bone scans are notoriously falsely negative in multiple myeloma as the lesions are purely lytic with little reactive bone formation.

Question 5534

Topic: 10. Pathology and Oncology

A 14-year-old male presents with worsening knee pain. Radiographs reveal a destructive metaphyseal lesion in the distal femur with a periosteal reaction forming a Codman triangle. Biopsy is performed. Which of the following histologic findings is essential to definitively diagnose the most likely primary bone tumor?

. Small round blue cells forming Homer-Wright rosettes
. Production of osteoid by malignant mesenchymal cells
. A uniform cartilage cap overlying mature trabecular bone
. Sheets of mononuclear cells interspersed with multinucleated giant cells
. Nests of uniform cells with prominent nucleoli and scant cytoplasm

Correct Answer & Explanation

. Production of osteoid by malignant mesenchymal cells

Explanation

The clinical and radiographic presentation is classic for osteosarcoma. The defining histologic hallmark required to diagnose osteosarcoma is the production of unmineralized osteoid or immature bone directly by malignant, pleomorphic mesenchymal cells.

Question 5535

Topic: 10. Pathology and Oncology

A 16-year-old female undergoes neoadjuvant chemotherapy followed by wide surgical resection for a conventional high-grade osteosarcoma of the distal femur. What is the most critical prognostic indicator of long-term overall survival in this patient?

. Initial tumor volume on MRI
. Percentage of tumor necrosis on histologic evaluation
. Type of endoprosthetic reconstruction used
. Preoperative alkaline phosphatase levels
. Distance of the tumor from the articular cartilage

Correct Answer & Explanation

. Percentage of tumor necrosis on histologic evaluation

Explanation

The degree of tumor necrosis following neoadjuvant chemotherapy is the single best predictor of overall survival. A good response is defined as greater than 90% necrosis on histologic mapping of the resected specimen.

Question 5536

Topic: 10. Pathology and Oncology

A 45-year-old male presents with a large, destructive lesion in the distal femur. An incisional biopsy is planned. Which of the following principles is considered standard of care to avoid compromising future limb-salvage surgery?

. Utilize a transverse incision to minimize tension on the skin closure.
. Ensure meticulous hemostasis to prevent a post-operative hematoma.
. Place the biopsy tract outside the planned definitive resection bed.
. Dissect through multiple intermuscular planes to locate the tumor.
. Use a tourniquet and exsanguinate the limb with an Esmarch bandage prior to inflation.

Correct Answer & Explanation

. Ensure meticulous hemostasis to prevent a post-operative hematoma.

Explanation

Meticulous hemostasis is critical during tumor biopsy to prevent a hematoma, which can spread tumor cells to adjacent un-involved compartments. Biopsy incisions must be longitudinal, placed within the planned resection tract, and exsanguination with an Esmarch is contraindicated to prevent systemic embolization.

Question 5537

Topic: 10. Pathology and Oncology

According to the Enneking surgical staging system for benign musculoskeletal tumors, a Stage 3 lesion is best described by which of the following characteristics?

. Latent, intracapsular and asymptomatic
. Active, expansile but contained within the natural bone barrier
. Low-grade malignant, intracompartmental
. Aggressive, symptomatic, and breeches the tumor capsule into surrounding tissues
. High-grade malignant with extracompartmental spread

Correct Answer & Explanation

. Active, expansile but contained within the natural bone barrier

Explanation

Enneking staging for benign tumors includes Stage 1 (Latent - asymptomatic, static), Stage 2 (Active - symptomatic, expansile but respects anatomical barriers), and Stage 3 (Aggressive - symptomatic, breaks through the capsule into surrounding tissues or extracompartmental spaces).

Question 5538

Topic: 10. Pathology and Oncology

A 65-year-old male presents with severe back pain and fatigue. Laboratory investigations reveal normocytic anemia, hypercalcemia, and an elevated total protein with normal albumin. Radiographs show multiple punched-out lytic lesions in the skull. Which of the following is the most definitive test for confirming the suspected diagnosis?

. Serum alkaline phosphatase
. Serum protein electrophoresis (SPEP) and bone marrow biopsy
. Flow cytometry of peripheral blood
. Technetium-99m whole body bone scan
. Prostate-specific antigen (PSA) levels

Correct Answer & Explanation

. Serum protein electrophoresis (SPEP) and bone marrow biopsy

Explanation

The clinical picture (CRAB: hyperCalcemia, Renal involvement, Anemia, Bone lytic lesions) is highly suggestive of Multiple Myeloma. The most definitive diagnostic step includes SPEP to detect the monoclonal M-spike and a bone marrow biopsy confirming >10% clonal plasma cells. Bone scans are typically cold in myeloma.

Question 5539

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with a diaphyseal femur lesion showing an 'onion-skin' periosteal reaction. Biopsy reveals uniform small round blue cells. Which of the following chromosomal translocations is the most characteristic diagnostic marker for this patient's condition?

. t(9;22)
. t(11;22)
. t(12;16)
. t(X;18)
. t(2;13)

Correct Answer & Explanation

. t(11;22)

Explanation

The clinical and histologic picture describes Ewing sarcoma. This tumor is classically associated with the t(11;22)(q24;q12) translocation in over 90% of cases, resulting in the EWS-FLI1 fusion protein. t(X;18) is associated with synovial sarcoma, t(12;16) with myxoid liposarcoma, and t(2;13) with alveolar rhabdomyosarcoma.

Question 5540

Topic: 10. Pathology and Oncology

A 14-year-old boy is diagnosed with conventional osteosarcoma of the distal femur. Biopsy confirms high-grade osteoblastic osteosarcoma. Which of the following genetic alterations is most frequently associated with the pathogenesis of this specific tumor?

. t(11;22)(q24;q12)
. t(X;18)(p11;q11)
. Mutations in the RB1 and TP53 tumor suppressor genes
. Amplification of the MDM2 gene
. t(2;13)(q35;q14)

Correct Answer & Explanation

. Mutations in the RB1 and TP53 tumor suppressor genes

Explanation

Conventional high-grade osteosarcoma is frequently associated with mutations in the RB1 (Retinoblastoma) and TP53 genes. Ewing sarcoma is associated with t(11;22). Synovial sarcoma is associated with t(X;18). MDM2 amplification is characteristic of parosteal osteosarcoma and low-grade central osteosarcoma. t(2;13) is seen in alveolar rhabdomyosarcoma.

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