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10. Pathology and Oncology MCQs

Practice Set 283 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 5641

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with a diaphysial lesion of the femur with an 'onion skin' periosteal reaction. Biopsy reveals small, round blue cells. Cytogenetic analysis of this tumor will most likely demonstrate which of the following translocations?

. 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 characterized by the t(11;22)(q24;q12) translocation, resulting in the EWS-FLI1 fusion gene in approximately 85-90% of cases. t(X;18) is seen in synovial sarcoma, t(12;16) in myxoid liposarcoma, and t(2;13) in alveolar rhabdomyosarcoma.

Question 5642

Topic: 10. Pathology and Oncology

A 24-year-old male presents with a slowly enlarging, painless mass deep in the thigh near the knee joint. MRI shows a well-defined, heterogeneous mass adjacent to the joint capsule but not involving the intra-articular space. Biopsy reveals a biphasic pattern of spindle cells and epithelial-like cells. Which cytogenetic abnormality is characteristic of this tumor?

. t(11;22) (q24;q12)
. t(X;18) (p11;q11)
. t(12;16) (q13;p11)
. t(9;22) (q22;q12)
. MDM2 amplification

Correct Answer & Explanation

. t(X;18) (p11;q11)

Explanation

Synovial sarcoma classically presents in young adults near large joints. The classic biphasic histological pattern (spindle and epithelial cells) and the pathognomonic t(X;18) translocation resulting in the SYT-SSX fusion gene are characteristic.

Question 5643

Topic: 10. Pathology and Oncology

A 62-year-old male presents with back pain, anemia, hypercalcemia, and acute renal failure. Radiographs show multiple punched-out lytic lesions in the skull and spine. Serum protein electrophoresis reveals an M-spike. Which of the following laboratory findings is most specific for determining the prognosis and tumor burden in this patient?

. Serum alkaline phosphatase levels
. Urine Bence Jones proteins
. Serum Beta-2 microglobulin
. C-reactive protein
. Erythrocyte sedimentation rate (ESR)

Correct Answer & Explanation

. Serum Beta-2 microglobulin

Explanation

The patient has Multiple Myeloma. Serum Beta-2 microglobulin is a highly specific marker used alongside albumin levels in the International Staging System (ISS) for Multiple Myeloma to determine prognosis and overall tumor burden. Higher levels correlate with a poorer prognosis.

Question 5644

Topic: 10. Pathology and Oncology

Which of the following is considered the most significant prognostic factor for long-term overall survival in a patient with high-grade conventional osteosarcoma of the distal femur?

. Age of the patient at presentation
. Absolute tumor size at presentation
. Specific histologic subtype (e.g., osteoblastic vs. chondroblastic)
. Percentage of tumor necrosis following neoadjuvant chemotherapy
. Initial serum alkaline phosphatase level

Correct Answer & Explanation

. Percentage of tumor necrosis following neoadjuvant chemotherapy

Explanation

The histologic response to neoadjuvant chemotherapy, specifically the percentage of tumor necrosis, is the most important prognostic factor for survival in conventional osteosarcoma. Greater than 90% necrosis (good responder) is associated with a significantly higher survival rate.

Question 5645

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with a painful, swollen thigh. Radiographs show a permeative diaphyseal lesion with an 'onion skin' periosteal reaction. Biopsy confirms a small round blue cell tumor. Which of the following chromosomal translocations is most characteristic of this diagnosis?

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

Correct Answer & Explanation

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

Explanation

Ewing sarcoma is classically associated with the t(11;22)(q24;q12) translocation, which results in the EWS-FLI1 fusion protein in approximately 85% of cases. t(X;18) is seen in synovial sarcoma, t(12;16) in myxoid liposarcoma, and t(2;13) in alveolar rhabdomyosarcoma.

Question 5646

Topic: 10. Pathology and Oncology

A 20-year-old male presents with deep, aching night pain in his tibia that is dramatically relieved by aspirin. Imaging reveals a 1 cm radiolucent nidus surrounded by dense reactive sclerosis. Which of the following is true regarding the pathophysiology or treatment of this lesion?

. It carries a 10% risk of malignant transformation to osteosarcoma
. Surgical excision requires wide margins to prevent metastasis
. The nidus produces high levels of prostaglandins, specifically PGE2
. Radiofrequency ablation is contraindicated due to high recurrence rates
. It is most commonly found in the epiphysis of long bones

Correct Answer & Explanation

. The nidus produces high levels of prostaglandins, specifically PGE2

Explanation

Osteoid osteoma is a benign bone-forming tumor characterized by a small nidus (< 2 cm) that produces high levels of prostaglandins (PGE2), which mediates the severe night pain and explains the dramatic relief with NSAIDs/aspirin. Radiofrequency ablation is the modern treatment of choice if medical management fails.

Question 5647

Topic: 10. Pathology and Oncology

A 65-year-old female presents with a destructive lytic lesion in the proximal femur. Biopsy reveals sheets of plasma cells. Which of the following tests is LEAST useful in the initial staging of her systemic disease?

. Serum protein electrophoresis (SPEP)
. Urine protein electrophoresis (UPEP)
. Technetium-99m bone scan
. Skeletal survey
. Serum free light chain assay

Correct Answer & Explanation

. Technetium-99m bone scan

Explanation

Technetium-99m bone scans rely on osteoblastic activity and are notoriously falsely negative in Multiple Myeloma. This disease primarily features pure osteoclastic (lytic) lesions, making a skeletal survey or low-dose whole-body CT the preferred imaging modality.

Question 5648

Topic: 10. Pathology and Oncology

A 14-year-old male presents with a painful, swollen thigh and fever. Radiographs show a permeative diaphyseal lesion with an onion-skin periosteal reaction. Cytogenetic analysis is most likely to reveal which of the following translocations?

. 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 radiographic presentation is classic for Ewing Sarcoma. The disease is characterized by the t(11;22) translocation in over 90% of cases, resulting in the EWS-FLI1 fusion protein.

Question 5649

Topic: 10. Pathology and Oncology

Which of the following genetic alterations is most closely associated with a markedly increased risk of developing both osteosarcoma and bilateral retinoblastoma?

. EWS-FLI1 translocation
. Inactivation of the RB1 gene
. Amplification of the MDM2 gene
. Mutation of the GNAS gene
. APC gene mutation

Correct Answer & Explanation

. Inactivation of the RB1 gene

Explanation

The RB1 (retinoblastoma) gene is a tumor suppressor gene. Inactivation or loss of heterozygosity of RB1 is the hallmark of hereditary retinoblastoma. Patients with this mutation have a significantly increased risk (often 500-fold) of developing secondary primary malignancies, most notably osteosarcoma. EWS-FLI1 is associated with Ewing sarcoma, MDM2 with low-grade central osteosarcoma and parosteal osteosarcoma, GNAS with fibrous dysplasia, and APC with familial adenomatous polyposis and Gardner syndrome.

Question 5650

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with knee pain. Radiographs show a sunburst periosteal reaction in the distal femur. Biopsy confirms osteosarcoma. Mutations in which two tumor suppressor genes are most commonly associated with the pathogenesis of this tumor?

. BRCA1 and BRCA2
. APC and MSH2
. Rb and p53
. NF1 and NF2
. WT1 and RET

Correct Answer & Explanation

. Rb and p53

Explanation

Osteosarcoma is strongly associated with mutations in the retinoblastoma (Rb) gene (as seen in hereditary retinoblastoma) and the p53 gene (as seen in Li-Fraumeni syndrome). Both are critical tumor suppressor genes that regulate the cell cycle.

Question 5651

Topic: Bone Tumors

The 'fallen leaf' (or 'fallen fragment') sign on a plain radiograph is virtually pathognomonic for which of the following benign bone lesions?

. Aneurysmal bone cyst (ABC)
. Unicameral bone cyst (UBC)
. Non-ossifying fibroma (NOF)
. Chondroblastoma
. Osteoid osteoma

Correct Answer & Explanation

. Unicameral bone cyst (UBC)

Explanation

The 'fallen leaf' sign occurs when a portion of the cortical bone fractures and falls into the fluid-filled cavity of a Unicameral (simple) bone cyst. Because it is a single fluid-filled cavity lacking internal septations or solid tissue, the bone fragment settles at the dependent portion of the cyst, which is pathognomonic for a UBC.

Question 5652

Topic: 10. Pathology and Oncology

A 32-year-old woman presents with knee pain. Radiographs reveal an eccentric, lytic epiphyseal lesion of the distal femur. Biopsy confirms Giant Cell Tumor of bone. Which of the following represents the neoplastic cell population and its characteristic mutation?

. Multinucleated giant cells with a GNAS mutation
. Mononuclear stromal cells with an H3F3A mutation
. Osteoblasts with a p53 mutation
. Chondrocytes with an IDH1 mutation
. Multinucleated giant cells with an H3F3A mutation

Correct Answer & Explanation

. Mononuclear stromal cells with an H3F3A mutation

Explanation

In Giant Cell Tumor (GCT) of bone, the true neoplastic cells are the mononuclear spindle-like stromal cells, not the multinucleated giant cells (which are reactive osteoclasts). The neoplastic mononuclear cells characteristically harbor a mutation in the H3F3A gene and express RANKL to recruit the giant cells.

Question 5653

Topic: Bone Tumors

A 68-year-old man presents with diffuse bone pain and a pathological fracture of the proximal humerus. Laboratory testing shows anemia, hypercalcemia, and a monoclonal spike on serum protein electrophoresis. Which of the following imaging modalities is notoriously insensitive for detecting the skeletal lesions associated with this condition?

. Plain radiography
. Computed tomography (CT)
. Magnetic resonance imaging (MRI)
. Technetium-99m bone scan
. Positron emission tomography (PET)

Correct Answer & Explanation

. Technetium-99m bone scan

Explanation

The patient has multiple myeloma. The lytic lesions of multiple myeloma are characterized by pure osteoclastic overactivity with virtually no osteoblastic response. Therefore, a Technetium-99m bone scan (which relies on osteoblastic activity) is typically 'cold' or falsely negative.

Question 5654

Topic: 10. Pathology and Oncology

A 24-year-old male presents with a slowly enlarging, painless mass around his knee joint. MRI shows a soft tissue mass adjacent to, but not within, the joint space. Biopsy reveals a biphasic pattern of spindle and epithelial cells. Which specific chromosomal translocation is characteristic of this pathology?

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

Correct Answer & Explanation

. t(X;18)

Explanation

Synovial sarcoma is characterized by the t(X;18) translocation, which leads to the SYT-SSX fusion gene. It commonly presents in young adults as an extra-articular soft tissue mass near a large joint.

Question 5655

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with knee pain. Radiographs demonstrate a mixed lytic and sclerotic lesion in the distal femoral metaphysis with periosteal reaction forming a Codman's triangle. Following biopsy confirming high-grade classic osteosarcoma, what is the most appropriate next step in management?

. Immediate surgical resection followed by radiation therapy
. Neoadjuvant chemotherapy followed by wide surgical resection
. Radiation therapy alone
. Amputation without prior chemotherapy
. Neoadjuvant radiation followed by wide surgical resection

Correct Answer & Explanation

. Neoadjuvant chemotherapy followed by wide surgical resection

Explanation

The standard of care for high-grade classic osteosarcoma includes neoadjuvant chemotherapy followed by wide surgical resection (limb salvage if possible), and then adjuvant chemotherapy. Osteosarcoma is generally radioresistant.

Question 5656

Topic: Bone Tumors

A 7-year-old girl is diagnosed with acute hematogenous osteomyelitis of the proximal tibia. In children, why is the metaphysis the most common initial location for hematogenous bacterial seeding?

. Presence of a nutrient artery with high flow velocity
. Lack of a periosteal layer in the metaphyseal region
. Sluggish blood flow in venous sinusoids adjacent to the physis
. Absence of macrophages in the metaphyseal bone marrow
. Direct connection between the metaphyseal vessels and the joint space

Correct Answer & Explanation

. Sluggish blood flow in venous sinusoids adjacent to the physis

Explanation

The metaphyseal vasculature adjacent to the physis features sharp capillary loops that transition into large venous sinusoids. This creates an area of sluggish blood flow and lower oxygen tension, acting as an ideal nidus for bacterial settling and proliferation.

Question 5657

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with a diaphyseal femur tumor exhibiting an 'onion-skin' periosteal reaction. A biopsy is performed. Which specific chromosomal translocation is most likely responsible for this malignancy?

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

Correct Answer & Explanation

. t(11;22)

Explanation

The clinical and radiographic presentation is classic for Ewing sarcoma. Ewing sarcoma is characteristically driven by the t(11;22) translocation, which results in the EWS-FLI1 fusion protein.

Question 5658

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with a permeative lytic lesion in the diaphysis of his left femur with an associated 'onion-skin' periosteal reaction. A biopsy confirms a small round blue cell tumor. Which of the following chromosomal translocations and resulting fusion proteins is most characteristic of this diagnosis?

. t(11;22) resulting in EWS-FLI1
. t(X;18) resulting in SYT-SSX
. t(12;16) resulting in TLS-CHOP
. t(2;13) resulting in PAX3-FKHR
. t(9;22) resulting in BCR-ABL

Correct Answer & Explanation

. t(11;22) resulting in EWS-FLI1

Explanation

The clinical presentation and histology are classic for Ewing sarcoma. Over 85% of Ewing sarcomas are characterized by a t(11;22)(q24;q12) translocation, which fuses the EWS gene on chromosome 22 with the FLI1 gene on chromosome 11, resulting in the EWS-FLI1 fusion protein. t(X;18) is associated with synovial sarcoma. t(12;16) is seen in myxoid liposarcoma.

Question 5659

Topic: 10. Pathology and Oncology
In a patient with classic high-grade intramedullary osteosarcoma, which of the following histologic findings after neoadjuvant chemotherapy is the most significant prognostic factor for long-term survival?
. Presence of multi-nucleated giant cells
. Complete absence of mitotic figures
. Greater than 90% tumor necrosis
. Conversion from osteoblastic to chondroblastic matrix
. A distinct fibrous pseudocapsule at the tumor margins

Correct Answer & Explanation

. Greater than 90% tumor necrosis

Explanation

The degree of tumor necrosis after neoadjuvant chemotherapy is the most important prognostic factor in osteosarcoma. According to the Huvos grading system, a 'good response' is defined as >90% necrosis (Grade III or IV), which strongly correlates with significantly improved long-term survival and disease-free intervals.

Question 5660

Topic: 10. Pathology and Oncology
The Enneking (Musculoskeletal Tumor Society) surgical staging system for malignant bone tumors utilizes histologic grade, anatomic setting, and the presence of metastasis. A high-grade sarcoma that has extended beyond the fascial boundaries of its compartment of origin, without regional or distant metastases, is classified as:
. Stage IA
. Stage IB
. Stage IIA
. Stage IIB
. Stage III

Correct Answer & Explanation

. Stage IIB

Explanation

In the Enneking system for malignant tumors, Stage I means low grade and Stage II means high grade. The letter 'A' signifies intracompartmental extension, while 'B' signifies extracompartmental extension. Stage III indicates the presence of any metastasis (regional or distant) regardless of grade or compartment. Thus, a high-grade, extracompartmental, non-metastatic tumor is Stage IIB.

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