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10. Pathology and Oncology MCQs

Practice Set 32 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 621

Topic: 10. Pathology and Oncology

What is the most common benign bone tumor of the hand?

. Enchondroma
. Osteochondroma
. Giant cell tumor
. Aneurysmal bone cyst
. Osteoid osteoma

Correct Answer & Explanation

. Enchondroma

Explanation

Correct Answer: AEnchondroma is by far the most common benign bone tumor of the hand, frequently found in the phalanges and metacarpals. Osteochondromas are common benign tumors but less frequent in the hand than enchondromas. Giant cell tumors are rare in the hand, and aneurysmal bone cysts and osteoid osteomas are also less common in this location compared to enchondromas.

Question 622

Topic: 10. Pathology and Oncology

A 12-year-old boy presents with an aggressive diaphyseal lesion in the fibula with "onion skin" periosteal reaction. Biopsy shows small round blue cells. Which chromosomal translocation is most commonly associated with this tumor?

. 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 associated with the t(11;22) translocation, resulting in the EWS-FLI1 fusion protein. t(X;18) is seen in synovial sarcoma, and t(12;16) in myxoid liposarcoma.

Question 623

Topic: Bone Tumors
A 55-year-old female presents with shoulder pain. Radiographs show a large radiolucent lesion in the proximal humerus with "rings and arcs" calcification and endosteal scalloping > 2/3 of the cortical thickness. What is the most appropriate definitive management?
. Intralesional curettage and bone grafting
. Wide surgical resection and reconstruction
. Neoadjuvant chemotherapy followed by wide resection
. Primary radiation therapy
. Observation with serial radiographs

Correct Answer & Explanation

. Wide surgical resection and reconstruction

Explanation

The clinical and radiographic findings suggest a conventional chondrosarcoma. Because conventional chondrosarcomas are highly resistant to chemotherapy and radiation, wide surgical resection is the standard of care.

Question 624

Topic: 10. Pathology and Oncology
A 15-year-old male with a distal femoral osteosarcoma undergoes neoadjuvant chemotherapy. Subsequent histologic analysis of the resected tumor shows 95% tumor necrosis. According to the Huvos grading system, which grade of response does this represent, and what is its prognostic significance?
. Grade I; poor prognosis
. Grade II; poor prognosis
. Grade III; favorable prognosis
. Grade IV; favorable prognosis
. Grade V; favorable prognosis

Correct Answer & Explanation

. Grade IV; favorable prognosis

Explanation

The Huvos grading system assesses tumor necrosis following chemotherapy. Grade III indicates 90-99% necrosis, while Grade IV represents 100% necrosis. >90% necrosis is considered a good histologic response and strongly correlates with improved survival.

Question 625

Topic: 10. Pathology and Oncology

A 65-year-old man presents with a pathologic fracture of the proximal femur. Biopsy reveals metastatic renal cell carcinoma. Preoperative planning for stabilization must include which of the following interventions to minimize a specific high-risk intraoperative complication?

. Prophylactic whole-brain radiation
. Administration of high-dose intravenous bisphosphonates
. Preoperative selective arterial embolization
. Placement of an inferior vena cava (IVC) filter
. Preoperative administration of systemic chemotherapy

Correct Answer & Explanation

. Preoperative selective arterial embolization

Explanation

Metastatic renal cell carcinoma and thyroid carcinoma lesions are notoriously hypervascular. Preoperative selective arterial embolization is critical to minimize the risk of massive, life-threatening intraoperative hemorrhage during stabilization.

Question 626

Topic: 10. Pathology and Oncology

A 45-year-old male undergoes a core needle biopsy for a deep soft tissue mass in his thigh. Histology demonstrates a biphasic pattern of spindle cells and epithelial cells. Cytogenetic analysis reveals a t(X;18) translocation. What is the most likely diagnosis?

. Synovial sarcoma
. Clear cell sarcoma
. Alveolar soft part sarcoma
. Epithelioid sarcoma
. Myxoid liposarcoma

Correct Answer & Explanation

. Synovial sarcoma

Explanation

Synovial sarcoma is characterized by the t(X;18) translocation, which creates the SYT-SSX fusion gene. It commonly presents in young to middle-aged adults with a deep-seated mass and can exhibit biphasic or monophasic histology.

Question 627

Topic: 10. Pathology and Oncology

A 12-year-old boy with a history of bilateral retinoblastoma presents with a painful mass in the distal femur. Biopsy confirms high-grade osteosarcoma. Which germline genetic mutation is most likely responsible for his underlying predisposition?

. TP53
. EXT1
. NF1
. RB1
. GNAS

Correct Answer & Explanation

. RB1

Explanation

Hereditary retinoblastoma is caused by a germline mutation in the RB1 tumor suppressor gene on chromosome 13. Patients with this mutation have a significantly increased risk of developing secondary primary malignancies, particularly osteosarcoma.

Question 628

Topic: 10. Pathology and Oncology

A 35-year-old male presents with incidental discovery of a lucent lesion with punctate calcifications in the metadiaphysis of the proximal phalanx of his hand. No pain or swelling. What is the most likely diagnosis?

. Chondrosarcoma
. Osteochondroma
. Enchondroma
. Fibrous Dysplasia
. Giant Cell Tumor

Correct Answer & Explanation

. Enchondroma

Explanation

Correct Answer: CEnchondromas are the most common benign cartilaginous tumors of the small bones of the hands and feet. Their classic radiographic appearance includes a lucent, intramedullary lesion with characteristic punctate or rings-and-arcs calcifications. The asymptomatic nature and typical location strongly favor enchondroma. Chondrosarcoma is less likely given the benign radiographic features and lack of symptoms. Osteochondroma is an exostosis, not intramedullary. Fibrous dysplasia has a ground-glass matrix. Giant cell tumor is typically epiphyseal and purely lytic.

Question 629

Topic: 10. Pathology and Oncology

When differentiating a solitary enchondroma from a low-grade chondrosarcoma in a long bone, which of the following radiographic features is most concerning for malignancy?

. Endosteal scalloping > 2/3 cortical thickness
. Punctate calcifications
. Intralesional fat signal on MRI
. Well-defined sclerotic border
. Absence of periosteal reaction

Correct Answer & Explanation

. Endosteal scalloping > 2/3 cortical thickness

Explanation

Correct Answer: ASignificant endosteal scalloping, particularly when it exceeds 2/3 of the cortical thickness, is a key radiographic indicator that suggests a more aggressive lesion, such as a low-grade chondrosarcoma, rather than a benign enchondroma. Punctate calcifications are typical for both. Intralesional fat is often seen in bone infarcts or areas of marrow, not typically a chondroid tumor. A well-defined sclerotic border and absence of periosteal reaction are features more consistent with a benign lesion.

Question 630

Topic: 10. Pathology and Oncology

A 40-year-old female has an asymptomatic enchondroma incidentally found in her proximal humerus during a shoulder MRI for rotator cuff impingement. The lesion measures 2x3cm, shows typical chondroid matrix calcifications, and no cortical breach or periosteal reaction. What is the most appropriate initial management?

. Immediate curettage and bone grafting
. Prophylactic internal fixation
. Annual radiographic follow-up
. Biopsy
. Systemic chemotherapy

Correct Answer & Explanation

. Annual radiographic follow-up

Explanation

Correct Answer: CFor an asymptomatic, radiographically benign-appearing enchondroma in a low-stress location like the proximal humerus, observation with serial radiographic follow-up (typically annual for 2-3 years) is the standard initial management. Surgical intervention, biopsy, or more aggressive treatments are reserved for symptomatic lesions, those with concerning radiographic features, or evidence of progression.

Question 631

Topic: 10. Pathology and Oncology
A 12-year-old boy presents with multiple enchondromas affecting the long bones of one limb and multiple cutaneous hemangiomas. This presentation is most consistent with:
. Ollier's disease
. Maffucci's syndrome
. McCune-Albright syndrome
. Neurofibromatosis Type 1
. Gorlin syndrome

Correct Answer & Explanation

. Maffucci's syndrome

Explanation

Maffucci's syndrome is characterized by multiple enchondromas and cutaneous hemangiomas. Ollier's disease involves multiple enchondromas without hemangiomas. McCune-Albright syndrome involves fibrous dysplasia, café-au-lait spots, and endocrine dysfunction. Neurofibromatosis Type 1 features neurofibromas and café-au-lait spots. Gorlin syndrome (Basal Cell Nevus Syndrome) involves multiple basal cell carcinomas and jaw keratocysts.

Question 632

Topic: 10. Pathology and Oncology

Histological examination of a typical enchondroma would reveal which of the following?

. Atypical chondrocytes with binucleation and myxoid changes
. Sheets of polygonal cells with eccentric nuclei and eosinophilic cytoplasm
. Nests of mature hyaline cartilage with scattered small chondrocytes in lacunae
. Spindle cells arranged in a storiform pattern
. Osteoclast-like giant cells with hemosiderin deposition

Correct Answer & Explanation

. Nests of mature hyaline cartilage with scattered small chondrocytes in lacunae

Explanation

Correct Answer: CA benign enchondroma typically consists of mature hyaline cartilage with small, uniform chondrocytes usually confined to single lacunae, or occasionally a few in pairs. There is no significant cellular atypia, binucleation, or myxoid change seen in low-grade chondrosarcoma. The other options describe features of other bone tumors: osteosarcoma (atypical cells), giant cell tumor (sheets of polygonal cells, osteoclast-like giant cells), fibrous histiocytoma (storiform pattern).

Question 633

Topic: 10. Pathology and Oncology

Which of the following conditions is associated with the highest risk of malignant transformation of enchondromas into chondrosarcoma?

. Solitary enchondroma
. Maffucci's syndrome
. Ollier's disease
. Fibrous dysplasia
. Osteochondromatosis

Correct Answer & Explanation

. Maffucci's syndrome

Explanation

Correct Answer: BMaffucci's syndrome carries the highest risk of malignant transformation (20-100%), often progressing to chondrosarcoma, but also to other malignancies. Ollier's disease also has a significant risk (25-50%), but generally lower than Maffucci's. Solitary enchondromas have a very low risk (<1%). Fibrous dysplasia and osteochondromatosis are different pathologies with their own distinct risks.

Question 634

Topic: 10. Pathology and Oncology

On MRI, a benign enchondroma typically demonstrates which of the following signal characteristics?

. Low signal on T1, very high signal on T2 with internal septations
. High signal on T1, low signal on T2 with solid enhancement
. Isointense on T1 and T2
. Heterogeneous signal with a fluid-fluid level
. Perilesional edema with cortical destruction

Correct Answer & Explanation

. Low signal on T1, very high signal on T2 with internal septations

Explanation

Correct Answer: ABenign hyaline cartilage, as seen in an enchondroma, typically appears low signal on T1-weighted images and very high signal on T2-weighted images due to its high water content. It often shows a lobulated configuration with internal septations and peripheral enhancement after contrast, but typically not solid or aggressive enhancement. Fluid-fluid levels are characteristic of aneurysmal bone cysts, and perilesional edema with cortical destruction is indicative of malignancy or infection.

Question 635

Topic: 10. Pathology and Oncology

Recent molecular studies have identified mutations in which gene family as commonly associated with enchondromas and low-grade chondrosarcomas?

. TP53
. MYC
. IDH
. RUNX2
. PTPN11

Correct Answer & Explanation

. IDH

Explanation

Correct Answer: CSomatic mutations in isocitrate dehydrogenase 1 (IDH1) and IDH2 genes are now recognized as common genetic alterations in both solitary enchondromas and central low-grade chondrosarcomas. These mutations lead to the production of an oncometabolite, 2-hydroxyglutarate (2-HG), which plays a role in chondrogenesis and malignant transformation.

Question 636

Topic: Bone Tumors

A 7-year-old boy with Hereditary Multiple Exostoses (HME) is noted to have a progressively worsening genu valgum deformity. His parents ask about the underlying cause of this angular deformity. Which of the following best describes the primary mechanism?

. Premature fusion of the entire physis due to the osteochondroma.
. Overgrowth of the physis on the concave side of the deformity.
. Asymmetric growth arrest or tethering of a portion of the physis by the osteochondroma.
. Mechanical block to joint motion leading to compensatory bone remodeling.
. Increased vascularity around the osteochondroma stimulating localized bone growth.

Correct Answer & Explanation

. Asymmetric growth arrest or tethering of a portion of the physis by the osteochondroma.

Explanation

Correct Answer: CAcademic Rationale:Angular deformities and limb length discrepancies in Hereditary Multiple Exostoses (HME) are primarily caused byasymmetric growth arrest or tethering of a portion of the physisby the osteochondroma. Osteochondromas arise from aberrant cartilage cells that escape the growth plate. When these lesions are located near or involve the physis, they can physically tether or distort a segment of the growth plate, leading to localized growth retardation or arrest. This asymmetric growth disturbance results in progressive angulation (e.g., genu valgum if the lateral side of the distal femur or proximal tibia physis is affected) and potential limb length discrepancies.Option A (Premature fusion of the entire physis):While growth arrest occurs, it's typically asymmetric and partial, not a complete premature fusion of the entire physis, which would lead to more uniform shortening rather than angulation.Option B (Overgrowth of the physis on the concave side):This is incorrect. The growth disturbance typically involves retardation or tethering, not overgrowth, and it's the affected side of the ph physis (often the concave side of the developing deformity) that is inhibited.Option D (Mechanical block to joint motion):While large osteochondromas can cause mechanical impingement and limit joint motion, this is a separate complication and not the primary mechanism for progressive angular deformities of the long bones themselves.Option E (Increased vascularity stimulating growth):Increased vascularity is not a recognized mechanism for causing angular deformities in HME; in fact, growth retardation is the issue.

Question 637

Topic: 10. Pathology and Oncology

A 38-year-old male with a known solitary osteochondroma of the distal femur, which has been asymptomatic since skeletal maturity, presents with new onset of dull, aching pain and a palpable increase in the size of the mass over the past 8 months. Radiographs show no obvious changes, but an MRI is ordered. Which MRI finding would be most concerning for malignant transformation?

. Presence of a fatty marrow signal within the bony stalk of the lesion.
. A cartilage cap thickness of 1.5 cm.
. A well-defined cleavage plane between the lesion and the adjacent muscle.
. Evidence of a new bursa formation overlying the osteochondroma.
. An irregular, lobulated cartilage cap measuring 3.2 cm with areas of enhancement.

Correct Answer & Explanation

. An irregular, lobulated cartilage cap measuring 3.2 cm with areas of enhancement.

Explanation

Correct Answer: EAcademic Rationale:The clinical scenario of new pain and increasing size in an adult with a previously quiescent osteochondroma is highly suspicious for malignant transformation to a secondary peripheral chondrosarcoma. The most critical MRI finding indicative of this transformation is anirregular, lobulated cartilage cap measuring greater than 2 cm (in adults) with areas of enhancement. A cartilage cap thickness exceeding 2 cm (or sometimes 3 cm, depending on the literature, but 2 cm is a common threshold) in an adult is a strong warning sign. Irregularity, lobulation, and enhancement suggest increased metabolic activity and potential malignant change within the cartilage cap.Option A (Fatty marrow signal):The presence of fatty marrow within the bony stalk is a normal feature of a benign osteochondroma, indicating continuity with the parent bone's medullary cavity, and is not a sign of malignancy.Option B (Cartilage cap thickness of 1.5 cm):While cartilage cap thickness is important, 1.5 cm is generally considered within the benign range for an adult. The threshold for concern is typically >2 cm.Option C (Well-defined cleavage plane):A well-defined cleavage plane between the lesion and adjacent soft tissues is a feature of a benign lesion. Malignant lesions often show invasion into surrounding soft tissues, blurring this plane.Option D (New bursa formation):Bursitis is a common complication of osteochondromas, causing pain and swelling, but it does not indicate malignant transformation. While it can mimic some symptoms, MRI would differentiate it from a malignant cartilage cap.

Question 638

Topic: 10. Pathology and Oncology

A 12-year-old girl presents with a painful mass on the posterior aspect of her distal femur. Radiographs confirm a pedunculated osteochondroma. Her pain is exacerbated by knee flexion and extension, and she reports a 'snapping' sensation. What is the most likely cause of her symptoms?

. Malignant transformation of the osteochondroma.
. Fracture through the stalk of the osteochondroma.
. Direct mechanical impingement on adjacent soft tissues or muscles.
. Compression of the popliteal artery leading to claudication.
. Development of a pseudoaneurysm.

Correct Answer & Explanation

. Direct mechanical impingement on adjacent soft tissues or muscles.

Explanation

Correct Answer: CAcademic Rationale:The description of a painful mass on the posterior distal femur, exacerbated by knee flexion and extension, and a 'snapping' sensation, is highly suggestive ofdirect mechanical impingement on adjacent soft tissues or muscles. A pedunculated osteochondroma in this location can irritate or impinge upon muscles (e.g., hamstrings, gastrocnemius) or tendons during joint movement, leading to pain and a palpable or audible snapping. This is a common symptomatic presentation for osteochondromas in areas of high motion.Option A (Malignant transformation):While possible, malignant transformation typically presents with persistent, dull aching pain, rapid growth, and often a larger, harder mass, rather than acute, movement-related snapping. It's also rare in a 12-year-old.Option B (Fracture through the stalk):A fracture would cause acute, severe pain, often following trauma, and would be visible on radiographs as a lucent line. The 'snapping' sensation is less typical for a fracture.Option D (Compression of the popliteal artery):Arterial compression would lead to symptoms of claudication (pain with exertion, relieved by rest), pallor, coolness, and diminished pulses, not typically a snapping sensation.Option E (Development of a pseudoaneurysm):A pseudoaneurysm would present as a rapidly enlarging, pulsatile mass with acute pain, which does not fit the 'snapping' description.

Question 639

Topic: 10. Pathology and Oncology

Which of the following statements accurately describes the typical growth pattern and cessation of an osteochondroma?

. Osteochondromas grow rapidly throughout life, independent of skeletal maturity.
. Growth is primarily driven by the bony stalk and continues indefinitely.
. Osteochondromas grow slowly during childhood, mimicking the adjacent physis, and typically cease growth at skeletal maturity.
. They exhibit cycles of rapid growth and spontaneous regression throughout adolescence.
. Growth accelerates significantly after skeletal maturity, often indicating a benign enlargement.

Correct Answer & Explanation

. Osteochondromas grow slowly during childhood, mimicking the adjacent physis, and typically cease growth at skeletal maturity.

Explanation

Correct Answer: CAcademic Rationale:Osteochondromas are benign lesions whose growth is directly linked to the activity of their overlying hyaline cartilage cap, which functions like a miniature growth plate. Therefore, theygrow slowly during childhood, mimicking the adjacent physis, and typically cease growth at skeletal maturitywhen the adjacent growth plate fuses. Once the physis ossifies, the cartilage cap of the osteochondroma also ossifies, and the lesion becomes quiescent.Option A (Rapidly throughout life):This is incorrect. Rapid growth throughout life is not typical for a benign osteochondroma.Option B (Driven by bony stalk, continues indefinitely):The growth is driven by the cartilage cap, not the bony stalk, and it does not continue indefinitely.Option D (Cycles of growth and regression):Osteochondromas do not typically regress; they either grow or become quiescent.Option E (Growth accelerates after skeletal maturity):Any growth or enlargement of an osteochondroma after skeletal maturity, especially if accompanied by pain, is a red flag for potential malignant transformation to a secondary chondrosarcoma, not a benign enlargement.

Question 640

Topic: Bone Tumors

A 22-year-old male presents with a painful mass in the popliteal fossa. Imaging reveals a large osteochondroma. Doppler ultrasound shows extrinsic compression of the popliteal artery with turbulent flow. Which of the following is the most appropriate definitive management for this patient?

. Observation with serial Doppler ultrasounds.
. Administration of systemic anticoagulants.
. Surgical excision of the osteochondroma with vascular repair if necessary.
. Percutaneous ethanol ablation of the osteochondroma.
. Physical therapy to improve popliteal muscle strength.

Correct Answer & Explanation

. Surgical excision of the osteochondroma with vascular repair if necessary.

Explanation

Correct Answer: CAcademic Rationale:The presence of an osteochondroma causing extrinsic compression of the popliteal artery with turbulent flow indicates a significant vascular complication that can lead to ischemia, pseudoaneurysm, or thrombosis. This is a surgical emergency. The most appropriate definitive management issurgical excision of the osteochondromato relieve the compression, with concurrent vascular repair or reconstruction if the artery has been damaged (e.g., pseudoaneurysm formation, intimal injury). This approach addresses both the cause (osteochondroma) and the consequence (vascular compromise).Option A (Observation):Observation is inappropriate given the acute vascular compromise.Option B (Systemic anticoagulants):Anticoagulants might be used if thrombosis has occurred, but they do not address the underlying mechanical compression and risk of arterial injury.Option D (Percutaneous ethanol ablation):This is not a standard or effective treatment for large osteochondromas, especially those causing vascular compression.Option E (Physical therapy):Physical therapy is not indicated for a mechanical vascular compression caused by a bony lesion.

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