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10. Pathology and Oncology MCQs

Practice Set 67 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 1321

Topic: 10. Pathology and Oncology

When planning a biopsy for a suspected extremity soft tissue sarcoma, which of the following principles is most critical for preserving limb-salvage surgical options?

. Using a transverse incision to minimize tension on the skin.
. Placing the biopsy tract in line with the definitive resection incision.
. Extracting the biopsy directly through the closest neurovascular bundle.
. Creating large, multi-compartment flaps to ensure adequate sampling.
. Performing the biopsy exclusively via an open excisional approach for tumors >5 cm.

Correct Answer & Explanation

. Placing the biopsy tract in line with the definitive resection incision.

Explanation

A biopsy tract must be placed longitudinally and in line with the planned definitive surgical excision. This ensures the entire tract can be excised en bloc with the tumor without contaminating additional compartments.

Question 1322

Topic: 10. Pathology and Oncology

A 55-year-old male presents with a large, destructive lesion in his right ilium with stippled 'popcorn' calcifications on plain film. Biopsy confirms a grade II conventional chondrosarcoma. Which of the following is the most appropriate primary treatment?

. Neoadjuvant chemotherapy followed by wide excision.
. Primary radiation therapy.
. Wide surgical excision alone.
. Curettage and cementation.
. Amputation only.

Correct Answer & Explanation

. Wide surgical excision alone.

Explanation

Conventional intermediate and high-grade chondrosarcomas are notably resistant to both chemotherapy and radiation. Wide surgical resection with negative margins is the definitive standard of care.

Question 1323

Topic: 10. Pathology and Oncology

A 35-year-old patient undergoes resection of a myxoid liposarcoma of the thigh. In addition to the standard staging CT of the chest, which of the following imaging modalities is highly recommended for staging this specific subtype of soft tissue sarcoma?

. MRI of the total spine
. CT of the brain
. Ultrasound of the liver
. PET scan focused solely on the lymphatic chain
. Bone densitometry (DEXA)

Correct Answer & Explanation

. MRI of the total spine

Explanation

Myxoid liposarcoma has a unique propensity for extrapulmonary metastasis, specifically to the spine and other bony sites. Total spine MRI is recommended as part of the staging workup.

Question 1324

Topic: 10. Pathology and Oncology

A 15-year-old male is diagnosed with high-grade osteosarcoma of the distal femur. He undergoes neoadjuvant chemotherapy. Which of the following histologic findings in the resected tumor specimen is the strongest predictor of long-term overall survival?

. Presence of chondroblastic differentiation
. Complete absence of mitotic figures in the remaining tumor margin
. >90% tumor necrosis
. High density of multinucleated giant cells
. Presence of a dense fibrous pseudocapsule

Correct Answer & Explanation

. >90% tumor necrosis

Explanation

The degree of tumor necrosis following neoadjuvant chemotherapy is the most critical prognostic factor for osteosarcoma. Greater than 90% necrosis indicates a good response and correlates with significantly better survival rates.

Question 1325

Topic: 10. Pathology and Oncology

A 42-year-old male presents with a painful lytic lesion in the epiphysis of the proximal humerus. Biopsy demonstrates malignant cells with abundant clear cytoplasm and distinct cell membranes, mixed with areas of chondroid matrix. This entity is most likely to be confused radiographically with which of the following benign lesions?

. Osteochondroma
. Chondroblastoma
. Unicameral bone cyst
. Enchondroma
. Aneurysmal bone cyst

Correct Answer & Explanation

. Chondroblastoma

Explanation

Clear cell chondrosarcoma typically presents in the epiphysis of long bones, which is also the classic location for a chondroblastoma. However, chondroblastoma usually occurs in skeletally immature patients (teens), whereas clear cell chondrosarcoma occurs in adults.

Question 1326

Topic: 10. Pathology and Oncology

A 20-year-old presents with a rapidly enlarging mass of the proximal tibia. Radiographs show a lytic, expansile lesion. MRI demonstrates multiple fluid-fluid levels, highly suggestive of an aneurysmal bone cyst (ABC). However, core biopsy reveals high-grade malignant cells producing a lacy, osteoid matrix. What is the diagnosis?

. Giant cell tumor of bone
. Secondary ABC
. Telangiectatic osteosarcoma
. Ewing sarcoma
. Chondromyxoid fibroma

Correct Answer & Explanation

. Telangiectatic osteosarcoma

Explanation

Telangiectatic osteosarcoma is a high-grade malignancy that radiographically mimics an aneurysmal bone cyst (showing fluid-fluid levels on MRI). The key to diagnosis is identifying high-grade sarcomatous cells producing osteoid in the septa.

Question 1327

Topic: 10. Pathology and Oncology

Which of the following describes the most common soft tissue sarcoma occurring in patients older than 50 years, which historically presented as a diagnosis of exclusion and consists of a storiform, pleomorphic cellular pattern?

. Synovial sarcoma
. Rhabdomyosarcoma
. Undifferentiated pleomorphic sarcoma (UPS)
. Epithelioid sarcoma
. Clear cell sarcoma

Correct Answer & Explanation

. Undifferentiated pleomorphic sarcoma (UPS)

Explanation

Undifferentiated pleomorphic sarcoma (UPS), formerly known as Malignant Fibrous Histiocytoma (MFH), is the most common soft tissue sarcoma in older adults. It is characterized by high-grade pleomorphic cells without a specific line of differentiation.

Question 1328

Topic: 10. Pathology and Oncology

A 65-year-old breast cancer survivor, who underwent lumpectomy and radiation therapy 10 years ago, presents with a new, rapidly growing, painful mass in the irradiated scapula. Biopsy demonstrates high-grade osteosarcoma. Which of the following features is most typical of radiation-induced sarcomas?

. They have an excellent prognosis with re-irradiation.
. They predominantly manifest as low-grade liposarcomas.
. They carry a significantly poorer prognosis compared to primary sarcomas of the same histologic type.
. They require a minimal latent period of only 6 months post-radiation.
. They only occur in the appendicular skeleton.

Correct Answer & Explanation

. They carry a significantly poorer prognosis compared to primary sarcomas of the same histologic type.

Explanation

Radiation-induced sarcomas (most commonly osteosarcoma or UPS) typically have a latency period of 4-10+ years. They are highly aggressive, resistant to therapy, and carry a significantly worse prognosis than primary de novo sarcomas.

Question 1329

Topic: 10. Pathology and Oncology

A 24-year-old male presents with a slowly enlarging, painless mass about his left knee. Biopsy reveals a biphasic tumor containing both spindle and epithelial cells. Which of the following chromosomal translocations is highly characteristic of this lesion?

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

Correct Answer & Explanation

. t(X;18)

Explanation

Synovial sarcoma is characterized by the t(X;18) translocation, resulting in the SYT-SSX fusion gene. It often presents in young adults near large joints and can exhibit a biphasic or monophasic histologic pattern.

Question 1330

Topic: 10. Pathology and Oncology

A 15-year-old boy with high-grade osteosarcoma of the distal femur completes neoadjuvant chemotherapy and undergoes surgical resection. What percentage of tumor necrosis is the standard threshold to classify the tumor as having a 'good response' to chemotherapy?

. 50%
. 75%
. 90%
. 95%
. 99%

Correct Answer & Explanation

. 90%

Explanation

The Huvos grading system assesses the histologic response to neoadjuvant chemotherapy in osteosarcoma. A 'good response' is classically defined as greater than or equal to 90% tumor necrosis.

Question 1331

Topic: 10. Pathology and Oncology

A 12-year-old girl presents with a destructive diaphyseal lesion of the fibula with a periosteal 'onion-skin' reaction. Immunohistochemistry is strongly positive for CD99. What is the most likely fusion gene associated with this malignancy?

. EWS-FLI1
. SYT-SSX
. FUS-DDIT3
. PAX3-FOXO1
. BCR-ABL

Correct Answer & Explanation

. EWS-FLI1

Explanation

Ewing sarcoma is characterized by the t(11;22) translocation, producing the EWS-FLI1 fusion protein. It typically presents as a permeative diaphyseal lesion with an aggressive periosteal reaction and strong CD99 positivity.

Question 1332

Topic: 10. Pathology and Oncology

A 45-year-old man undergoes excision of a deep intramuscular thigh mass. Histology demonstrates a 'chicken-wire' capillary network and lipoblasts. Which of the following genetic alterations is diagnostic for this tumor?

. t(12;16)
. t(X;18)
. MDM2 amplification
. t(2;13)
. t(11;22)

Correct Answer & Explanation

. t(12;16)

Explanation

Myxoid liposarcoma is characterized by the t(12;16) translocation, resulting in the FUS-DDIT3 fusion gene. It histologically exhibits a prominent 'chicken-wire' branching capillary network and has a propensity for extrapulmonary bone metastases.

Question 1333

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with a painful mass in his distal femur. Radiographs reveal a sunburst periosteal reaction and Codman's triangle. A biopsy is planned. Which of the following principles is critical when performing a biopsy for a suspected musculoskeletal sarcoma?

. Transverse incisions should be used for extremity lesions to improve cosmesis.
. The biopsy tract should be placed outside the planned definitive resection margin.
. Extensive hemostasis with a drain placed through a separate distant stab incision is required.
. The biopsy should be performed through the involved muscle compartment rather than intermuscular planes.
. A tourniquet should be inflated and then deflated before closure to ensure hematoma evacuation.

Correct Answer & Explanation

. The biopsy should be performed through the involved muscle compartment rather than intermuscular planes.

Explanation

Biopsies must be performed through the involved compartment to avoid contaminating unaffected intermuscular planes. A longitudinal incision is required so the entire tract can be excised during definitive surgery.

Question 1334

Topic: 10. Pathology and Oncology

A 16-year-old girl with high-grade conventional osteosarcoma of the proximal tibia undergoes neoadjuvant chemotherapy followed by limb-salvage surgery. Which of the following factors is the most important predictor of her overall survival?

. The specific type of surgical reconstruction utilized.
. The percentage of tumor necrosis observed in the resected specimen.
. The initial volume of the soft tissue mass.
. The patient's age at the time of diagnosis.
. The distance of the tumor from the joint line.

Correct Answer & Explanation

. The percentage of tumor necrosis observed in the resected specimen.

Explanation

The most important prognostic factor for overall survival in osteosarcoma is the histologic response to neoadjuvant chemotherapy. Tumor necrosis greater than 90% indicates a good response and correlates with improved survival.

Question 1335

Topic: 10. Pathology and Oncology

A 10-year-old boy presents with thigh pain and fever. Radiographs show a permeative, diaphyseal lesion in the femur with an onion-skin periosteal reaction. A biopsy confirms small round blue cells. Which of the following genetic translocations is most characteristic of this tumor?

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

Correct Answer & Explanation

. t(11;22)

Explanation

Ewing sarcoma is characterized by the t(11;22) translocation, resulting in the EWS-FLI1 fusion protein. t(X;18) is seen in synovial sarcoma, and t(9;22) in extraskeletal myxoid chondrosarcoma.

Question 1336

Topic: 10. Pathology and Oncology

A 28-year-old female presents with a slowly enlarging, painful mass on the dorsal aspect of her foot. Radiographs reveal soft tissue calcifications. Biopsy demonstrates a biphasic tumor with both epithelial and spindle cells. What is the most common route of metastasis for this specific sarcoma, and to which organ?

. Hematogenous spread to the liver
. Lymphatic spread to the regional lymph nodes
. Hematogenous spread to the lungs
. Direct extension to the adjacent bone
. Cerebrospinal fluid seeding to the brain

Correct Answer & Explanation

. Hematogenous spread to the lungs

Explanation

The patient has a synovial sarcoma, which frequently presents with calcifications and biphasic histology. Like most soft tissue sarcomas, it most commonly metastasizes to the lungs via hematogenous spread, despite having a higher rate of lymph node metastasis than other sarcomas.

Question 1337

Topic: 10. Pathology and Oncology

A 55-year-old male presents with a large, painful, destructive lesion in his proximal humerus. Biopsy confirms a high-grade conventional chondrosarcoma. Which of the following is the most appropriate definitive management?

. Neoadjuvant chemotherapy followed by wide surgical excision.
. Wide surgical excision alone.
. Intralesional curettage, adjuvant phenol, and cementation.
. Definitive radiation therapy.
. Amputation followed by adjuvant chemotherapy.

Correct Answer & Explanation

. Wide surgical excision alone.

Explanation

Conventional chondrosarcomas are notoriously resistant to both chemotherapy and radiation therapy. The definitive treatment for high-grade and intermediate-grade conventional chondrosarcoma is wide surgical excision.

Question 1338

Topic: 10. Pathology and Oncology

A 38-year-old male presents with a 2-year history of insidious left knee pain, intermittent swelling, and mechanical symptoms. Over the past 6 months, symptoms progressed to constant pain and persistent, boggy effusion. Prior aspirations yielded dark, serosanguinous fluid, negative for crystals and infection. Physical examination reveals a doughy effusion, significant synovial thickening, and a 5° flexion contracture with maximal flexion to 100°. Plain radiographs show a moderate effusion, preserved joint space, and subtle marginal subchondral erosions. Given this clinical picture, which of the following is the most likely diagnosis?

. Septic Arthritis
. Rheumatoid Arthritis
. Pigmented Villonodular Synovitis (PVNS)
. Synovial Chondromatosis
. Hemophilic Arthropathy

Correct Answer & Explanation

. Pigmented Villonodular Synovitis (PVNS)

Explanation

Correct Answer: C - Pigmented Villonodular Synovitis (PVNS)The patient's presentation is classic for Pigmented Villonodular Synovitis (PVNS), now classified as diffuse Tenosynovial Giant Cell Tumor (TGCT). Key features include the insidious onset of chronic knee pain, persistent boggy (doughy) joint effusion, mechanical symptoms, and recurrent aspirations yielding dark, serosanguinous fluid. The preserved joint space on radiographs despite chronic symptoms, coupled with subtle marginal erosions, further supports PVNS. The synovial thickening palpable on examination is also characteristic of the proliferative nature of PVNS.A. Septic Arthritis:This is unlikely. While the patient has a chronic effusion and pain, prior synovial fluid analyses were negative for infection (Gram stain and cultures), and there are no systemic signs of infection (fever, chills, warmth, erythema).B. Rheumatoid Arthritis:While RA can cause synovial hypertrophy and erosions, the presentation is typically polyarticular, and synovial fluid is inflammatory with a high WBC count (often >2,000 cells/mm3) and a neutrophil predominance. The patient's normal ESR/CRP and mononuclear fluid analysis make RA less likely, especially in a monoarticular presentation without other systemic features.D. Synovial Chondromatosis:This condition is characterized by the formation of cartilaginous or osteocartilaginous loose bodies within the joint. While it can cause mechanical symptoms and chronic pain, the synovial fluid is typically clear to yellow, and radiographs or MRI would show calcified loose bodies, which were not described as the primary finding in this case.E. Hemophilic Arthropathy:This is ruled out by the patient's negative history of bleeding diatheses or coagulopathies, and normal coagulation panel results. While hemophilic arthropathy also causes recurrent hemarthroses and hemosiderin deposition, it occurs in patients with known clotting factor deficiencies.

Question 1339

Topic: 10. Pathology and Oncology

Histopathological evaluation is crucial for definitive diagnosis of Tenosynovial Giant Cell Tumor (TGCT), diffuse type (PVNS). Microscopically, PVNS is characterized by a hypercellular proliferation of mononuclear cells, multinucleated osteoclast-like giant cells, foamy lipid-laden macrophages, and extensive hemosiderin deposits. Beyond these cellular features, what is the specific genetic abnormality frequently associated with the pathogenesis of PVNS?

. Trisomy 21
. t(11;22) translocation (Ewing sarcoma)
. t(1;2)(p13;q37) translocation leading to CSF1 overexpression
. Deletion of the p53 tumor suppressor gene
. BRAF V600E mutation

Correct Answer & Explanation

. t(1;2)(p13;q37) translocation leading to CSF1 overexpression

Explanation

Correct Answer: C - t(1;2)(p13;q37) translocation leading to CSF1 overexpressionThe case explicitly details the pathogenesis: "The mononuclear cells frequently demonstrate a specific genetic translocation, t(1;2)(p13;q37), which results in the fusion of the Colony Stimulating Factor 1 (CSF1) gene with the Collagen Type VI Alpha 3 (COL6A3) promoter. This translocation leads to the localized overproduction of CSF1, which acts as a chemoattractant, recruiting the massive influx of non-neoplastic macrophages and giant cells that form the bulk of the tumor mass." This genetic abnormality and its consequence are central to understanding PVNS.A. Trisomy 21:This is associated with Down syndrome and is not related to PVNS.B. t(11;22) translocation (Ewing sarcoma):This is the characteristic translocation found in Ewing sarcoma, a malignant bone tumor, not PVNS.D. Deletion of the p53 tumor suppressor gene:While p53 mutations are common in many cancers, it is not the primary or specific genetic driver for PVNS.E. BRAF V600E mutation:This mutation is notably associated with melanoma, papillary thyroid cancer, and hairy cell leukemia, but not PVNS.

Question 1340

Topic: 10. Pathology and Oncology

Based on the MRI findings demonstrating diffuse, exuberant, hypertrophic synovitis involving all compartments of the knee joint, including the suprapatellar pouch, medial and lateral gutters, intercondylar notch, and posterior joint recesses, how is this patient's condition most accurately classified according to the World Health Organization (WHO) system, and what is its typical recurrence rate after surgical synovectomy?

. Localized TGCT; low recurrence rate (<5%)
. Diffuse TGCT; high recurrence rate (20-50%)
. Synovial Sarcoma; variable recurrence rate depending on grade
. Osteochondroma; no recurrence after complete excision
. Reactive Synovitis; recurrence dependent on underlying cause

Correct Answer & Explanation

. Diffuse TGCT; high recurrence rate (20-50%)

Explanation

Correct Answer: B - Diffuse TGCT; high recurrence rate (20-50%)The case clearly states: "Based on the MRI findings demonstrating involvement of the suprapatellar pouch, gutters, intercondylar notch, and posterior recesses, this patient presented withDiffuse TGCT of the knee." It further elaborates on the WHO classification: "Diffuse TGCT (formerly Diffuse PVNS): Involves the entire synovial lining of a joint, bursa, or tendon sheath. It is locally aggressive, infiltrative, and carries a notoriously high recurrence rate (ranging from 20% to 50% in the literature) even after extensive surgical synovectomy."A. Localized TGCT; low recurrence rate (<5%):Localized TGCT (formerly Giant Cell Tumor of Tendon Sheath) presents as a discrete nodule, typically in digits, and has a low recurrence rate after excision. This does not match the diffuse involvement described.C. Synovial Sarcoma; variable recurrence rate depending on grade:Synovial sarcoma is a rare, aggressive malignancy, distinct from PVNS. While it can occur in joints, its classification and prognosis are different.D. Osteochondroma; no recurrence after complete excision:Osteochondroma is a benign bone tumor, not a synovial lesion, and is not relevant to this case.E. Reactive Synovitis; recurrence dependent on underlying cause:Reactive synovitis is a general term for inflammation of the synovium. While PVNS involves synovial inflammation, it is a specific tumor-like condition, not merely reactive, and has a distinct recurrence profile.

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