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10. Pathology and Oncology MCQs

Practice Set 279 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 5561

Topic: 10. Pathology and Oncology

A 24-year-old male presents with a deep, slow-growing soft tissue mass in his thigh. Histological evaluation following biopsy reveals a biphasic tumor pattern. Which of the following chromosomal translocations is most characteristic of this malignancy?

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

Correct Answer & Explanation

. t(X;18)

Explanation

The scenario describes synovial sarcoma, which classically demonstrates a biphasic or monophasic histologic pattern. It characteristically features the t(X;18) chromosomal translocation, resulting in the SYT-SSX fusion gene.

Question 5562

Topic: 10. Pathology and Oncology

A 65-year-old male presents with a pathologic fracture of the proximal femur. Biopsy reveals sheets of malignant plasma cells. Which of the following interleukins is considered a critical osteoclast-activating factor in the pathogenesis of this disease?

. IL-1
. IL-2
. IL-6
. IL-10
. IL-12

Correct Answer & Explanation

. IL-6

Explanation

Multiple myeloma cells characteristically secrete IL-6, which is a potent stimulator of osteoclastogenesis. The excessive osteoclast activity leads to the characteristic punched-out lytic bone lesions and hypercalcemia seen in the disease.

Question 5563

Topic: 10. Pathology and Oncology

A 25-year-old male presents with a slow-growing, painful mass near his knee. MRI shows a soft tissue mass intimately associated with the joint capsule. Biopsy confirms a soft tissue sarcoma. Cytogenetic analysis reveals a specific chromosomal translocation resulting in the SSX-SYT fusion gene. Which of the following translocations is associated with this tumor?

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

Correct Answer & Explanation

. t(X;18)

Explanation

The patient has synovial sarcoma, which is classically associated with the t(X;18) chromosomal translocation, resulting in the fusion of the SYT gene on chromosome 18 with one of the SSX genes on the X chromosome. t(11;22) is seen in Ewing sarcoma, t(12;16) in myxoid liposarcoma, and t(2;13) in alveolar rhabdomyosarcoma.

Question 5564

Topic: 10. Pathology and Oncology

A 22-year-old male develops sudden tachycardia, muscle rigidity, and a rapid rise in core body temperature 30 minutes after induction of general anesthesia with sevoflurane and succinylcholine for an emergency femur fracture fixation. What is the primary cellular defect responsible for this condition?

. Mutation in the voltage-gated sodium channel
. Acetylcholinesterase deficiency
. Mutation in the ryanodine receptor (RYR1)
. Defect in the dihydropyridine receptor
. Mitochondrial ATP synthase mutation

Correct Answer & Explanation

. Mutation in the ryanodine receptor (RYR1)

Explanation

The patient is experiencing malignant hyperthermia. The classic trigger agents are volatile anesthetics (e.g., sevoflurane, halothane) and depolarizing muscle relaxants (succinylcholine). The primary underlying defect in the vast majority of cases is a mutation in the RYR1 gene, which encodes the ryanodine receptor on the sarcoplasmic reticulum. This leads to unregulated release of calcium into the myoplasm, causing sustained muscle contraction and hypermetabolism. Treatment involves immediate discontinuation of the trigger, supportive care, and administration of dantrolene.

Question 5565

Topic: 10. Pathology and Oncology

A 66-year-old male presents with severe back pain and a pathological compression fracture of the L4 vertebra. Laboratory evaluation reveals hypercalcemia, normocytic anemia, and an elevated serum protein electrophoresis (SPEP) demonstrating an M-spike. Radiographs of the skull show multiple 'punched-out' lytic lesions. What is the most likely diagnosis?

. Osteosarcoma
. Metastatic Prostate Cancer
. Multiple Myeloma
. Ewing Sarcoma
. Chondrosarcoma

Correct Answer & Explanation

. Multiple Myeloma

Explanation

The combination of advanced age, hypercalcemia, anemia, classic 'punched-out' lytic skeletal lesions, and an M-spike (monoclonal gammopathy) on SPEP is highly characteristic of Multiple Myeloma, a plasma cell dyscrasia and the most common primary malignancy of bone in adults.

Question 5566

Topic: Bone Tumors

A 65-year-old male presents with a pathologic fracture of the proximal humerus. Laboratory workup reveals hypercalcemia, anemia, and elevated total serum protein. Radiographs show multiple 'punched-out' lytic lesions in the skull and pelvis. Which of the following tests is most definitive for confirming the underlying diagnosis?

. Serum alkaline phosphatase levels
. Prostate-specific antigen (PSA)
. Serum and urine protein electrophoresis (SPEP/UPEP)
. Bone scan (technetium-99m)
. Erythrocyte sedimentation rate (ESR)

Correct Answer & Explanation

. Serum and urine protein electrophoresis (SPEP/UPEP)

Explanation

The clinical presentation (pathologic fracture, hypercalcemia, anemia, punched-out lytic lesions) is classic for Multiple Myeloma. The most definitive initial non-invasive diagnostic tests are serum and urine protein electrophoresis (SPEP and UPEP) with immunofixation to detect a monoclonal (M) protein spike. Bone scans are often falsely negative in multiple myeloma because the lesions are purely lytic.

Question 5567

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with knee pain. Radiographs show a destructive metaphyseal lesion of the distal femur with a "sunburst" periosteal reaction. If a biopsy is performed, mutation in which of the following genes is most commonly implicated in the pathogenesis of this tumor?

. EXT1
. RB1
. GNAS
. SH3BP2
. Runx2

Correct Answer & Explanation

. RB1

Explanation

Osteosarcoma is the most common primary malignant bone tumor in children, frequently occurring in the distal femur. It is heavily associated with mutations in tumor suppressor genes, particularly RB1 (Retinoblastoma gene) and TP53.

Question 5568

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 blue round cells. Which cytogenetic abnormality is most classically associated with this tumor?

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

Correct Answer & Explanation

. t(11;22)

Explanation

Ewing sarcoma is classically associated with the t(11;22)(q24;q12) translocation, which results in the EWS-FLI1 fusion protein. This drives the neoplastic proliferation of the tumor.

Question 5569

Topic: Bone Tumors

A 19-year-old male complains of severe, aching thigh pain that is worse at night and dramatically relieved by ibuprofen. Radiographs show a dense cortical sclerosis with a 1 cm radiolucent nidus. The intense pain is mediated by local overproduction of which substance?

. Interleukin-1 (IL-1)
. Prostaglandin E2 (PGE2)
. Tumor necrosis factor-alpha (TNF-a)
. Bradykinin
. Substance P

Correct Answer & Explanation

. Prostaglandin E2 (PGE2)

Explanation

Osteoid osteomas classically cause nocturnal pain that is dramatically relieved by NSAIDs. This is due to the nidus producing high levels of Prostaglandin E2 (PGE2), which causes local vasodilation and nerve fiber sensitization.

Question 5570

Topic: 10. Pathology and Oncology

A 25-year-old male presents with a slow-growing, painful mass near his knee joint. Biopsy reveals a biphasic tumor with both epithelial and spindle cell components. Which of the following chromosomal translocations is diagnostic for this malignancy?

. t(11;22) EWS-FLI1
. t(12;16) FUS-DDIT3
. t(X;18) SYT-SSX
. t(2;13) PAX3-FOXO1
. t(12;22) EWS-ATF1

Correct Answer & Explanation

. t(X;18) SYT-SSX

Explanation

The clinical and histological presentation (biphasic components near a joint) is classic for Synovial Sarcoma. The pathognomonic chromosomal translocation for synovial sarcoma is t(X;18), which creates the SYT-SSX fusion gene. t(11;22) is found in Ewing sarcoma. t(12;16) is seen in myxoid liposarcoma. t(2;13) is characteristic of alveolar rhabdomyosarcoma. t(12;22) is seen in clear cell sarcoma.

Question 5571

Topic: Bone Tumors

A 19-year-old male presents with dull, aching thigh pain that is distinctly worse at night and reliably relieved by ibuprofen. Imaging reveals a 1.2 cm radiolucent nidus with surrounding sclerosis in the proximal femoral diaphysis. What is the primary molecular mechanism responsible for this patient's pain?

. Increased local production of Interleukin-1
. Excessive release of Prostaglandin E2 by the nidus
. Direct mechanical nerve compression by the tumor
. Histamine release from mast cells in the reactive zone
. Subperiosteal microhemorrhage

Correct Answer & Explanation

. Excessive release of Prostaglandin E2 by the nidus

Explanation

Osteoid osteomas classically present with night pain relieved by NSAIDs. This is due to the high concentration of cyclooxygenase (COX) enzymes within the nidus, which produce copious amounts of Prostaglandin E2 (PGE2). PGE2 lowers the threshold of local nociceptors. NSAIDs block COX, halting PGE2 production and rapidly relieving the pain.

Question 5572

Topic: 10. Pathology and Oncology

A 12-year-old boy presents with an aggressive diaphyseal lesion in his femur with an 'onion skin' periosteal reaction. A biopsy is planned. Which specific chromosomal translocation is most characteristically associated with this pathology?

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

Correct Answer & Explanation

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

Explanation

Ewing sarcoma is classically associated with the t(11;22)(q24;q12) translocation, resulting in the EWS-FLI1 fusion protein. Synovial sarcoma is associated with t(X;18), and alveolar rhabdomyosarcoma with t(2;13).

Question 5573

Topic: Bone Tumors

A 19-year-old male complains of severe night pain in his proximal tibia that is dramatically relieved by NSAIDs. Radiographs show a small radiolucent nidus surrounded by dense sclerotic bone. What is the primary mechanism by which this lesion causes pain?

. Microfractures within the sclerotic bone
. Compression of adjacent peripheral nerves
. High levels of prostaglandin E2 production by the nidus
. Rapid expansile growth stretching the periosteum
. Release of histamines and bradykinins

Correct Answer & Explanation

. High levels of prostaglandin E2 production by the nidus

Explanation

Osteoid osteomas produce high levels of prostaglandins (specifically PGE2) which cause severe, localized pain, characteristically worse at night. This is why nonsteroidal anti-inflammatory drugs (NSAIDs) provide dramatic symptomatic relief.

Question 5574

Topic: Bone Tumors

A 15-year-old boy presents with progressive distal thigh pain. Imaging shows a sunburst periosteal reaction and Codman's triangle in the distal femur. A biopsy confirms high-grade intramedullary osteosarcoma. What is the standard treatment protocol?

. Radiation therapy followed by wide surgical resection
. Neoadjuvant chemotherapy, wide surgical resection, and adjuvant chemotherapy
. Immediate amputation
. Neoadjuvant radiation, amputation, and adjuvant chemotherapy
. Intralesional curettage and bone grafting

Correct Answer & Explanation

. Neoadjuvant chemotherapy, wide surgical resection, and adjuvant chemotherapy

Explanation

The standard of care for high-grade conventional osteosarcoma is neoadjuvant (preoperative) chemotherapy, followed by wide surgical resection, and concluding with adjuvant chemotherapy. Osteosarcoma is generally radioresistant.

Question 5575

Topic: 10. Pathology and Oncology

A 22-year-old male presents with a slow-growing soft tissue mass in his foot. Biopsy reveals a biphasic tumor pattern. Cytogenetic analysis shows a t(X;18)(p11;q11) translocation. What is the most likely diagnosis?

. Ewing sarcoma
. Synovial sarcoma
. Alveolar rhabdomyosarcoma
. Clear cell sarcoma
. Myxoid liposarcoma

Correct Answer & Explanation

. Synovial sarcoma

Explanation

The t(X;18) translocation is the diagnostic hallmark of synovial sarcoma, resulting in the SYT-SSX fusion gene. Despite its name, this aggressive soft tissue sarcoma rarely arises within actual joint spaces.

Question 5576

Topic: 10. Pathology and Oncology

A 40-year-old female presents with severe pain in the forefoot and a sensation of 'walking on a marble.' She is diagnosed with a Morton's neuroma in the third web space. Histological examination of the excised tissue would most likely reveal which of the following?

. A true benign neoplastic proliferation of Schwann cells
. Perineural fibrosis, local vascular changes, and endoneurial edema
. Malignant peripheral nerve sheath tumor characteristics
. Granulomatous inflammation with giant cells
. Demyelination with extensive axonal wallerian degeneration

Correct Answer & Explanation

. Perineural fibrosis, local vascular changes, and endoneurial edema

Explanation

Morton's neuroma is not a true neuroma (neoplasm). It is an entrapment neuropathy characterized by perineural fibrosis, local vascular changes, and endoneurial edema.

Question 5577

Topic: 10. Pathology and Oncology

A 15-year-old girl presents with persistent distal thigh pain. Radiographs reveal a destructive, permeative lesion in the distal femoral metaphysis with a 'sunburst' periosteal reaction and elevation of the periosteum (Codman's triangle). Which of the following histological findings is required to confirm the most likely diagnosis?

. Sheets of small blue round cells with scant cytoplasm
. Osteoid production directly by malignant mesenchymal cells
. Abundant multinucleated giant cells in a background of mononuclear cells
. A disorganized cartilage cap with endochondral ossification
. Monoclonal plasma cells producing light chains

Correct Answer & Explanation

. Osteoid production directly by malignant mesenchymal cells

Explanation

The clinical and radiographic findings strongly suggest osteosarcoma. The histologic hallmark required for the diagnosis of osteosarcoma is the production of osteoid matrix directly by malignant spindle cells.

Question 5578

Topic: 10. Pathology and Oncology

A 10-year-old boy presents with low-grade fever, weight loss, and mid-thigh pain. Radiographs of the femur show a large diaphyseal lesion with an 'onion-skin' periosteal reaction. Biopsy reveals sheets of small round blue cells. This malignancy is classically associated with which of the following chromosomal translocations?

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

Correct Answer & Explanation

. t(11;22)

Explanation

Ewing sarcoma typically presents in the diaphysis of long bones with an 'onion-skin' periosteal reaction and small round blue cells on histology. It is characterized by the t(11;22) translocation, producing the EWS-FLI1 fusion protein.

Question 5579

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with progressive knee pain. Radiographs reveal a metaphyseal, permeative, bone-forming lesion in the distal femur with a 'sunburst' periosteal reaction. Biopsy confirms high-grade osteosarcoma. Which of the following is the most important prognostic factor for this patient's survival?

. Anatomic location of the tumor
. Histologic subtype of osteosarcoma
. Tumor volume at initial presentation
. Degree of tumor necrosis following neoadjuvant chemotherapy
. Serum alkaline phosphatase levels

Correct Answer & Explanation

. Degree of tumor necrosis following neoadjuvant chemotherapy

Explanation

The most important prognostic factor for patients with high-grade osteosarcoma is the histologic response to neoadjuvant chemotherapy, specifically the percentage of tumor necrosis. Greater than 90% necrosis indicates a good response and correlates with improved survival.

Question 5580

Topic: 10. Pathology and Oncology

A 14-year-old boy is diagnosed with high-grade osteosarcoma of the distal femur. He undergoes neoadjuvant chemotherapy followed by limb-salvage resection. Which of the following is the most significant prognostic factor for his long-term survival?

. Initial tumor volume
. Patient age at diagnosis
. Percentage of tumor necrosis found in the resected specimen
. Specific chemotherapy agents used
. Presence of a Codman's triangle on initial radiograph

Correct Answer & Explanation

. Percentage of tumor necrosis found in the resected specimen

Explanation

The percentage of tumor necrosis following neoadjuvant chemotherapy (histologic response) is the single most important prognostic factor for long-term survival in patients with high-grade osteosarcoma. A good response is typically defined as greater than 90% necrosis.

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