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10. Pathology and Oncology MCQs

Practice Set 280 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 5581

Topic: 10. Pathology and Oncology

A 32-year-old woman presents with knee pain. Radiographs reveal an eccentric, lytic lesion in the proximal tibial epiphysis extending to the subchondral bone, with no sclerotic margin. Biopsy confirms mononuclear cells and multinucleated giant cells. What is the most appropriate primary surgical treatment?

. Wide en bloc resection and endoprosthetic reconstruction
. Radiation therapy
. Intralesional extended curettage with high-speed burr and bone cement
. Amputation
. Curettage and isolated cancellous autografting

Correct Answer & Explanation

. Intralesional extended curettage with high-speed burr and bone cement

Explanation

Giant cell tumors of bone are aggressive but benign lesions. The standard treatment is intralesional extended curettage (using a high-speed burr, phenol, or argon beam) followed by packing with PMMA bone cement, which provides immediate structural support and causes thermal necrosis of residual microscopic cells.

Question 5582

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with a diaphyseal femur lesion showing an 'onion skin' periosteal reaction. A core biopsy confirms Ewing sarcoma. Which of the following genetic translocations is most characteristically associated with this diagnosis?

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

Correct Answer & Explanation

. t(11;22)

Explanation

Ewing sarcoma is classically characterized by the t(11;22)(q24;q12) translocation, which results in the EWS-FLI1 fusion protein. t(9;22) is associated with CML (Philadelphia chromosome) and myxoid chondrosarcoma; t(2;13) with alveolar rhabdomyosarcoma; t(12;16) with myxoid liposarcoma; and t(X;18) with synovial sarcoma.

Question 5583

Topic: 10. Pathology and Oncology

In a patient presenting with high-grade, non-metastatic intramedullary osteosarcoma, which of the following is widely considered the most important prognostic factor for long-term survival?

. The initial volume of the tumor
. The specific histological subtype (e.g., osteoblastic vs. chondroblastic)
. The degree of histologic necrosis following neoadjuvant chemotherapy
. The patient's age at the time of diagnosis
. The anatomic location of the primary lesion

Correct Answer & Explanation

. The degree of histologic necrosis following neoadjuvant chemotherapy

Explanation

The most significant prognostic factor for overall survival in high-grade osteosarcoma is the histological response of the tumor to neoadjuvant chemotherapy. A 'good response' is typically defined as greater than 90% tumor necrosis at the time of surgical resection.

Question 5584

Topic: 10. Pathology and Oncology

A 15-year-old boy presents with knee pain. Radiographs show a destructive, bone-forming lesion in the distal femoral metaphysis with a "sunburst" periosteal reaction. Mutations in which of the following tumor suppressor genes are most classically associated with this condition?

. t(11;22)
. RB1
. EXT1
. GNAS
. t(X;18)

Correct Answer & Explanation

. RB1

Explanation

The clinical and radiographic presentation is classic for osteosarcoma. Osteosarcoma is strongly associated with mutations in the RB1 (retinoblastoma) and TP53 (Li-Fraumeni syndrome) tumor suppressor genes.

Question 5585

Topic: 10. Pathology and Oncology

A 16-year-old male presents with deep knee pain and a mixed lytic-sclerotic distal femur lesion with periosteal elevation on radiographs. Biopsy confirms osteosarcoma. Mutations in which of the following tumor suppressor genes are most strongly associated with the pathogenesis of this tumor?

. BRCA1 and BRCA2
. Rb1 and TP53
. APC and MLH1
. PTEN and VHL
. SMAD4 and CDH1

Correct Answer & Explanation

. Rb1 and TP53

Explanation

Osteosarcoma is strongly associated with mutations in the retinoblastoma (Rb1) and TP53 tumor suppressor genes. Patients with hereditary retinoblastoma or Li-Fraumeni syndrome (mutated TP53) are at significantly increased risk for developing this malignancy.

Question 5586

Topic: 10. Pathology and Oncology

A 12-year-old boy presents with a destructive diaphyseal lesion of the femur with an onion-skin periosteal reaction. Cytogenetic analysis is most likely to reveal which of the following translocations?

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

Correct Answer & Explanation

. t(11;22)

Explanation

The clinical and radiographic presentation is classic for Ewing sarcoma. Over 90% of Ewing sarcomas are characterized by the t(11;22) translocation, which fuses the EWS gene to the FLI1 gene.

Question 5587

Topic: 10. Pathology and Oncology

A 45-year-old female presents with multiple lytic bone lesions, nephrolithiasis, and profound generalized muscle weakness. Radiographs reveal subperiosteal bone resorption on the radial aspect of her middle phalanges. Her laboratory profile will most likely demonstrate:

. Low serum calcium and high PTH
. High serum calcium and high PTH
. Normal serum calcium and normal PTH
. Low serum calcium and low PTH
. High serum calcium and low PTH

Correct Answer & Explanation

. High serum calcium and high PTH

Explanation

The patient's presentation of "bones, stones, moans, and groans" with subperiosteal resorption and brown tumors is classic for primary hyperparathyroidism. This condition is characterized by inappropriately elevated PTH and resulting hypercalcemia.

Question 5588

Topic: 10. Pathology and Oncology

A patient with Li-Fraumeni syndrome presents with a distal femur osteosarcoma. Which of the following gene mutations is most directly responsible for the increased susceptibility to osteosarcoma in this syndrome?

. p53
. Rb
. EXT1
. GNAS
. NF1

Correct Answer & Explanation

. p53

Explanation

Li-Fraumeni syndrome is an autosomal dominant disorder caused by germline mutations in the p53 tumor suppressor gene. It significantly increases the risk of developing several cancers, most notably osteosarcoma.

Question 5589

Topic: 10. Pathology and Oncology

A 28-year-old male presents with a slow-growing, painful soft tissue mass near his knee joint. MRI shows an extra-articular mass with focal calcifications. A biopsy is performed. Which of the following chromosomal translocations is most characteristic of the likely diagnosis?

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

Correct Answer & Explanation

. t(X;18)

Explanation

The clinical picture describes a synovial sarcoma, which classically presents in young adults as a slow-growing soft tissue mass near joints (though rarely intra-articular) and may contain calcifications. The characteristic chromosomal translocation is t(X;18)(p11;q11), leading to the SYT-SSX fusion gene. t(11;22) is seen in Ewing sarcoma; t(9;22) in myxoid chondrosarcoma; t(12;16) in myxoid liposarcoma; and t(2;13) in alveolar rhabdomyosarcoma.

Question 5590

Topic: Bone Tumors
A 32-year-old male presents with dull, aching pain in his right anterior thigh that is significantly worse at night and dramatically relieved by taking ibuprofen. Radiographs show a distinct area of cortical thickening with a small (<1.5 cm) radiolucent nidus. Which of the following is the most appropriate initial management?
. En bloc resection
. Curettage and bone grafting
. Radiofrequency ablation
. Observation with NSAIDs
. Radiation therapy

Correct Answer & Explanation

. Observation with NSAIDs

Explanation

The clinical and radiographic presentation is classic for an osteoid osteoma. Excessive prostaglandin production by the nidus causes the characteristic night pain that is relieved by NSAIDs. The first line of treatment is typically a trial of medical management (Observation with NSAIDs), as a significant proportion will spontaneously 'burn out' and resolve over several years. If medical management fails or is poorly tolerated, radiofrequency ablation (RFA) is the definitive treatment of choice.

Question 5591

Topic: 10. Pathology and Oncology

A 7-year-old boy presents with localized back pain. Radiographs demonstrate a flattened vertebra (vertebra plana) with no associated soft tissue mass. He has no systemic symptoms. A biopsy reveals histiocytes with folded nuclei, and electron microscopy shows Birbeck granules. What is the most likely diagnosis?

. Ewing sarcoma
. Leukemia
. Aneurysmal bone cyst
. Langerhans cell histiocytosis
. Osteoblastoma

Correct Answer & Explanation

. Langerhans cell histiocytosis

Explanation

Langerhans cell histiocytosis (LCH), particularly the solitary form historically known as eosinophilic granuloma, classically presents as vertebra plana in children. The diagnosis is confirmed histologically by the presence of Birbeck granules (tennis racket-shaped organelles) on electron microscopy.

Question 5592

Topic: 10. Pathology and Oncology

A 19-year-old male complains of a dull, aching pain in his posterior spine that has progressively worsened over 6 months. The pain is not significantly relieved by NSAIDs. Radiographs show a 2.5 cm expansile radiolucent lesion in the posterior elements of L3. What is the most likely diagnosis?

. Osteoid osteoma
. Osteoblastoma
. Aneurysmal bone cyst
. Eosinophilic granuloma
. Enchondroma

Correct Answer & Explanation

. Osteoblastoma

Explanation

Osteoblastomas are benign bone-forming tumors that are histologically similar to osteoid osteomas but are distinguished by being larger (>2 cm), more locally aggressive, and having pain that is typically dull, aching, and not consistently relieved by NSAIDs. They frequently occur in the posterior elements of the spine.

Question 5593

Topic: 10. Pathology and Oncology

A 25-year-old male presents with a slow-growing, calcified mass near his right knee. A biopsy demonstrates a biphasic pattern consisting of both epithelial and spindle cells. Which of the following chromosomal translocations is diagnostic for this tumor?

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

Correct Answer & Explanation

. t(X;18)

Explanation

The clinical and histologic description is classic for synovial sarcoma, which frequently presents as a calcified periarticular mass in young adults. It is characterized by the t(X;18)(p11;q11) translocation, resulting in the SYT-SSX fusion gene.

Question 5594

Topic: 10. Pathology and Oncology

The Mirels scoring system is used to predict the risk of pathologic fracture in patients with metastatic bone lesions and guide the decision for prophylactic fixation. Which of the following parameters assigns the maximum of 3 points in this scoring system?

. Location in the upper extremity
. A blastic nature of the lesion
. Moderate functional pain
. A lytic nature of the lesion
. Lesion size less than 1/3 of the cortical diameter

Correct Answer & Explanation

. A lytic nature of the lesion

Explanation

The Mirels scoring system assigns points (1 to 3) across four categories: Site (Upper limb=1, Lower limb=2, Peritrochanteric=3), Pain (Mild=1, Moderate=2, Functional=3), Lesion character (Blastic=1, Mixed=2, Lytic=3), and Size (<1/3=1, 1/3-2/3=2, >2/3=3). A lytic lesion is assigned 3 points.

Question 5595

Topic: 10. Pathology and Oncology

A 15-year-old male presents with persistent distal femur pain. Radiographs reveal a sunburst periosteal reaction and a Codman's triangle. Biopsy confirms high-grade intramedullary osteosarcoma. What is the most critical prognostic factor for long-term survival in this patient?

. Histologic subtype (osteoblastic vs. chondroblastic)
. Tumor size at presentation
. Percentage of tumor necrosis following neoadjuvant chemotherapy
. Presence of a pathologic fracture at presentation
. Serum alkaline phosphatase levels

Correct Answer & Explanation

. Percentage of tumor necrosis following neoadjuvant chemotherapy

Explanation

In the treatment of high-grade osteosarcoma, the histologic response to neoadjuvant chemotherapy (specifically, the percentage of tumor necrosis observed in the resected specimen) is the single most important prognostic indicator for long-term survival. Greater than 90% necrosis indicates a good response and significantly better overall prognosis.

Question 5596

Topic: 10. Pathology and Oncology

A 16-year-old male presents with severe thigh pain and a rapidly expanding mass following minor trauma. Radiographs show a purely lytic, expansile lesion in the distal femoral metaphysis. MRI demonstrates multiple fluid-fluid levels. Biopsy reveals blood-filled spaces lined by anaplasia and malignant cells producing a lacelike matrix. Which of the following is the most critical feature differentiating this lesion from an aneurysmal bone cyst (ABC)?

. Presence of multinucleated giant cells
. Fluid-fluid levels on MRI
. Expansile radiolucent appearance on plain radiographs
. Malignant cells producing osteoid matrix
. Location in the metaphysis of a long bone

Correct Answer & Explanation

. Malignant cells producing osteoid matrix

Explanation

The clinical and radiographic presentation of telangiectatic osteosarcoma is remarkably similar to that of an aneurysmal bone cyst (ABC), as both can present as expansile lytic lesions with fluid-fluid levels on MRI. The definitive differentiating factor is histological: telangiectatic osteosarcoma features highly atypical, malignant cells that produce a malignant osteoid matrix (often lacelike) within the septa, whereas an ABC is benign and lacks malignant cytology and malignant osteoid.

Question 5597

Topic: 10. Pathology and Oncology

A 60-year-old male undergoes wide resection of a proximal femur mass. Histologic examination reveals a distinct biphasic pattern consisting of islands of low-grade malignant hyaline cartilage sharply juxtaposed against a high-grade, non-cartilaginous spindle cell sarcoma, with no transitional zone between the two. What is the most accurate diagnosis?

. Clear cell chondrosarcoma
. Mesenchymal chondrosarcoma
. Dedifferentiated chondrosarcoma
. Osteosarcoma with chondroblastic differentiation
. Enchondroma with secondary malignant transformation

Correct Answer & Explanation

. Dedifferentiated chondrosarcoma

Explanation

The pathognomonic histologic feature of dedifferentiated chondrosarcoma is a bimorphic (biphasic) pattern characterized by a well-differentiated (low-grade) cartilaginous tumor abruptly transitioning into a highly anaplastic, high-grade non-cartilaginous sarcoma (often osteosarcoma, fibrosarcoma, or undifferentiated pleomorphic sarcoma). The lack of a transitional zone is a hallmark.

Question 5598

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with a painful mass in his left distal femur. Radiographs show a destructive, permeative lesion with a 'sunburst' periosteal reaction. Biopsy confirms high-grade osteosarcoma. Which of the following genetic alterations is most frequently associated with the pathogenesis of this condition?

. t(11;22)
. t(X;18)
. t(2;13)
. Retinoblastoma (Rb) gene and p53 mutations
. GNAS1 mutation

Correct Answer & Explanation

. Retinoblastoma (Rb) gene and p53 mutations

Explanation

High-grade intramedullary osteosarcoma is highly associated with mutations in tumor suppressor genes, specifically Rb and p53 (Li-Fraumeni syndrome). t(11;22) is characteristic of Ewing sarcoma. t(X;18) is seen in synovial sarcoma. t(2;13) is seen in alveolar rhabdomyosarcoma. GNAS1 mutations are associated with fibrous dysplasia.

Question 5599

Topic: Bone Tumors
A 60-year-old man presents with back pain, anemia, hypercalcemia, and renal insufficiency. Radiographs show multiple punched-out lytic lesions in the skull and pelvis. Which of the following imaging modalities is generally considered LEAST useful in identifying the full extent of his skeletal lesions?
. Technetium-99m bone scintigraphy
. Whole-body low-dose computed tomography (WBLDCT)
. Skeletal survey with plain radiographs
. Positron emission tomography (PET-CT)
. Magnetic resonance imaging (MRI)

Correct Answer & Explanation

. Technetium-99m bone scintigraphy

Explanation

Multiple myeloma lesions are purely osteolytic and lack the reactive osteoblastic bone formation required for uptake on a standard Technetium-99m bone scan. Therefore, bone scans often yield false-negative results in myeloma and are considered the least useful modality compared to WBLDCT, skeletal surveys, MRI, or PET-CT.

Question 5600

Topic: 10. Pathology and Oncology

A 65-year-old female with a history of breast cancer presents with progressive right thigh pain. Radiographs reveal a 3.5 cm lytic lesion in the peritrochanteric region of the proximal femur, occupying 60% of the cortical diameter. Which of the following parameters are utilized in the Mirels' scoring system to determine the indication for prophylactic internal fixation?

. Patient age, overall life expectancy, and tumor responsiveness to radiation
. Histological tumor grade, patient BMI, and lesion location
. Site of lesion, size of lesion, nature of lesion, and presence of pain
. Responsiveness of the primary tumor to systemic chemotherapy and hypercalcemia
. Cortical thickness, periosteal reaction, and surrounding soft tissue mass

Correct Answer & Explanation

. Site of lesion, size of lesion, nature of lesion, and presence of pain

Explanation

Mirels' criteria are used to quantify the risk of pathologic fracture in long bones affected by metastatic lesions. The score (ranging from 4 to 12) is based on four variables: Site (upper limb, lower limb, peritrochanteric), Pain (mild, moderate, functional/severe), Lesion nature (blastic, mixed, lytic), and Size (<1/3, 1/3-2/3, >2/3 cortical diameter). A score of 9 or greater indicates high risk and warrants prophylactic fixation.

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