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10. Pathology and Oncology MCQs

Practice Set 15 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 281

Topic: 10. Pathology and Oncology

Which histological feature is most characteristic of Grade 2 chondrosarcoma when differentiating it from Grade 1?

. Increased cellularity with a prominent myxoid stroma
. Extensive host bone entrapment without permeation
. Lack of binucleated cells
. Abundant calcified cartilage matrix
. Presence of multinucleated giant cells

Correct Answer & Explanation

. Extensive host bone entrapment without permeation

Explanation

Grade 2 chondrosarcomas demonstrate increased cellularity, nuclear atypia, and often prominent myxoid stroma compared to Grade 1. Host bone entrapment is a classic feature used to differentiate benign enchondroma from low-grade chondrosarcoma.

Question 282

Topic: 10. Pathology and Oncology

What is the most significant prognostic factor for long-term survival in a pediatric patient treated for a high-grade intramedullary osteosarcoma of the distal femur?

. Initial tumor volume
. Preoperative alkaline phosphatase levels
. Histologic response to neoadjuvant chemotherapy
. Type of definitive surgical resection (limb salvage vs. amputation)
. Presence of a pathological fracture at presentation

Correct Answer & Explanation

. Histologic response to neoadjuvant chemotherapy

Explanation

The degree of tumor necrosis following neoadjuvant chemotherapy is the most critical prognostic indicator in osteosarcoma. Greater than 90% tumor necrosis is associated with significantly higher long-term survival rates.

Question 283

Topic: Bone Tumors

The proximal humerus is the most common location of unicameral bone cysts. Which of the following is the second most common location:

. Distal radius
. Iliac wing
. Proximal femur
. Distal femur
. Proximal tibia

Correct Answer & Explanation

. Proximal femur

Explanation

The proximal femur is the second most common location for unicameral bone cysts. All other locations are distinctly less common.

Question 284

Topic: Bone Tumors

An 8-year old patient presents with pain in a unicameral bone cyst of the proximal femur. Which of the following treatments is most likely to prevent fracture:

. Intralesional steroid injection
. Intralesional bone marrow injection
. Intralesional injection of demineralized bone matrix
. C urettage and bone graft
. C urettage, bone graft, and internal fixation

Correct Answer & Explanation

. C urettage, bone graft, and internal fixation

Explanation

Injection of any substance has a risk of recurrence, even if the injection is repeated. Bone graft has a risk as well, but internal fixation decreases the risk of fracture.

Question 285

Topic: Bone Tumors

All of the following are common in McC une-Albright syndrome except:

. Precocious puberty
. Polyostotic fibrous dysplasia
. Cafu-au-lait spots
. Bowing of long bones
. Multiple osteocartilaginous exostoses

Correct Answer & Explanation

. Multiple osteocartilaginous exostoses

Explanation

McCune-Albright syndrome consists of polyostotic fibrous dysplasia, precocious puberty, and cafa-au-lait spots. Long bone deformity is almost universal. Multiple osteocartilaginous exostoses are not part of this syndrome.

Question 286

Topic: 10. Pathology and Oncology

Which of the following genetic translocations is most characteristically associated with primary aneurysmal bone cysts?

. t(11;22)
. t(16;17)
. t(X;18)
. t(2;13)
. t(12;16)

Correct Answer & Explanation

. t(16;17)

Explanation

Primary aneurysmal bone cysts are characterized by the t(16;17) translocation, which results in the upregulation of the USP6 gene. The t(11;22) translocation is associated with Ewing sarcoma, and t(X;18) is associated with synovial sarcoma.

Question 287

Topic: Bone Tumors

The classic nocturnal pain associated with an osteoid osteoma is primarily mediated by the high local concentration of which of the following substances?

. Histamine
. Prostaglandin E2
. Bradykinin
. Interleukin-1
. Tumor necrosis factor-alpha

Correct Answer & Explanation

. Prostaglandin E2

Explanation

Osteoid osteomas produce high levels of Prostaglandin E2 due to robust COX-2 expression within the nidus. This local PGE2 production explains the characteristic severe nocturnal pain and its dramatic relief with nonsteroidal anti-inflammatory drugs.

Question 288

Topic: Bone Tumors
A 12-year-old girl presents with a shepherd's crook deformity of the femur and café-au-lait spots with irregular borders. This condition is caused by a somatic mutation affecting which of the following genes?
. EXT1
. GNAS1
. NF1
. FGFR3
. SH3BP2

Correct Answer & Explanation

. GNAS1

Explanation

McCune-Albright syndrome, characterized by polyostotic fibrous dysplasia, endocrinopathy, and café-au-lait spots, is caused by a somatic activating mutation in the GNAS1 gene. This mutation impairs the GTPase activity of the alpha subunit of the Gs protein, leading to increased cAMP.

Question 289

Topic: 10. Pathology and Oncology

Following neoadjuvant chemotherapy and surgical resection for conventional high-grade osteosarcoma, which of the following represents the most significant prognostic factor for overall patient survival?

. Tumor size at initial presentation
. Specific histologic subtype
. Percentage of tumor necrosis in the resected specimen
. Preoperative serum alkaline phosphatase level
. Patient age at the time of diagnosis

Correct Answer & Explanation

. Percentage of tumor necrosis in the resected specimen

Explanation

The degree of tumor necrosis after neoadjuvant chemotherapy, quantified by Huvos grading, is the most critical prognostic indicator in conventional osteosarcoma. Greater than 90% tumor necrosis indicates a favorable response to chemotherapy and significantly improves overall survival.

Question 290

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with a permeative diaphyseal lesion of the femur with a periosteal "onion-skin" reaction. Immunohistochemical staining of a biopsy specimen is most likely to be strongly positive for which of the following?

. CD99
. S-100
. Cytokeratin
. Smooth muscle actin
. Desmin

Correct Answer & Explanation

. CD99

Explanation

Ewing sarcoma is a small round blue cell tumor that typically exhibits strong, diffuse membranous staining for CD99 (MIC2). S-100 is typically used to identify neural tumors and melanoma.

Question 291

Topic: 10. Pathology and Oncology

A 55-year-old man presents with a painful shoulder. Radiographs reveal a lytic lesion with "ring and arc" calcifications in the proximal humerus, and MRI shows endosteal scalloping greater than 2/3 of the cortical thickness. What is the most likely diagnosis?

. Enchondroma
. Chondrosarcoma
. Osteosarcoma
. Multiple myeloma
. Giant cell tumor

Correct Answer & Explanation

. Chondrosarcoma

Explanation

"Ring and arc" calcifications suggest a cartilaginous matrix. The presence of pain and deep endosteal scalloping (greater than 2/3 of the cortical thickness) are highly concerning imaging features for a low-grade chondrosarcoma rather than a benign enchondroma.

Question 292

Topic: 10. Pathology and Oncology

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

. 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) chromosomal translocation, resulting in the SYT-SSX fusion gene. It often presents as a deep, calcified soft tissue mass in the extremities of young adults.

Question 293

Topic: 10. Pathology and Oncology

A 10-year-old boy has an incidentally discovered eccentrically located, multi-loculated radiolucent lesion with a sclerotic margin in the distal tibial metaphysis. He is entirely asymptomatic. What is the most appropriate management?

. Core needle biopsy
. Curettage and bone grafting
. Prophylactic internal fixation
. Observation
. Radiofrequency ablation

Correct Answer & Explanation

. Observation

Explanation

This classic presentation represents a non-ossifying fibroma (NOF), a benign "do-not-touch" lesion. NOFs are typically asymptomatic and resolve spontaneously through progressive ossification as the child reaches skeletal maturity, requiring only observation.

Question 294

Topic: 10. Pathology and Oncology

A 15-year-old male presents with chronic knee pain. Radiographs reveal a 2 cm eccentric, radiolucent lesion with a fine sclerotic margin and central calcifications situated entirely within the proximal tibial epiphysis. What is the most likely diagnosis?

. Osteoid osteoma
. Chondroblastoma
. Unicameral bone cyst
. Enchondroma
. Osteochondroma

Correct Answer & Explanation

. Chondroblastoma

Explanation

Chondroblastoma is a rare, benign cartilaginous tumor that characteristically arises in the epiphysis or apophysis of skeletally immature patients. Histology typically reveals "chicken-wire" calcifications surrounding chondroblasts.

Question 295

Topic: Bone Tumors

A 65-year-old woman presents with back pain and generalized fatigue. Radiographs show multiple punched-out lytic lesions in her skull and pelvis. Laboratory tests show hypercalcemia and elevated creatinine. Which diagnostic test is most essential for confirming the underlying diagnosis?

. Serum alkaline phosphatase
. Serum protein electrophoresis
. Prostate-specific antigen level
. Thyroid stimulating hormone
. 24-hour urine cortisol

Correct Answer & Explanation

. Serum protein electrophoresis

Explanation

The clinical picture strongly suggests multiple myeloma, characterized by the CRAB criteria (HyperCalcemia, Renal failure, Anemia, Bone lesions). Serum protein electrophoresis (SPEP) is critical to identify the monoclonal M-protein spike associated with this plasma cell dyscrasia.

Question 296

Topic: 10. Pathology and Oncology

A 20-year-old patient with Multiple Hereditary Exostoses reports recent rapid growth and pain in a previously stable lesion on his proximal humerus. What is the most important imaging parameter to evaluate for malignant transformation?

. Presence of marrow continuity
. Cartilage cap thickness on MRI
. Sclerotic borders on plain radiograph
. Uptake intensity on bone scan
. Doppler blood flow on ultrasound

Correct Answer & Explanation

. Cartilage cap thickness on MRI

Explanation

Malignant transformation of an osteochondroma to a secondary chondrosarcoma is best evaluated by measuring the cartilage cap thickness on T2-weighted MRI. A cartilage cap thicker than 1.5 to 2.0 cm in a skeletally mature patient is highly concerning for malignancy.

Question 297

Topic: 10. Pathology and Oncology

Which of the following primary bone tumors characteristically arises in the diaphyseal region of long bones?

. Giant cell tumor
. Chondroblastoma
. Adamantinoma
. Clear cell chondrosarcoma
. Osteosarcoma

Correct Answer & Explanation

. Adamantinoma

Explanation

Adamantinoma is a rare, low-grade malignant bone tumor that classically occurs in the anterior cortex of the tibial diaphysis. In contrast, giant cell tumors and chondroblastomas are epiphyseal, and osteosarcoma is typically metaphyseal.

Question 298

Topic: 10. Pathology and Oncology

A 10-year-old child presents with a severe skeletal deformity characterized by multiple enchondromas combined with multiple superficial soft tissue hemangiomas. What is the proper eponym for this syndrome?

. Ollier disease
. Maffucci syndrome
. McCune-Albright syndrome
. Jaffe-Campanacci syndrome
. Mazabraud syndrome

Correct Answer & Explanation

. Maffucci syndrome

Explanation

Maffucci syndrome is defined by the concurrent presence of multiple enchondromatosis and soft tissue hemangiomas. Patients with Maffucci syndrome carry a significantly higher lifetime risk of malignant transformation (e.g., to chondrosarcoma) compared to those with Ollier disease.

Question 299

Topic: 10. Pathology and Oncology

Mazabraud syndrome is a rare genetic disorder characterized by the presence of polyostotic fibrous dysplasia in association with which of the following soft tissue lesions?

. Intramuscular myxomas
. Hemangiomas
. Neurofibromas
. Lipomas
. Desmoid tumors

Correct Answer & Explanation

. Intramuscular myxomas

Explanation

Mazabraud syndrome is characterized by the synchronous presentation of fibrous dysplasia of bone and intramuscular myxomas. The soft tissue myxomas frequently develop in the same anatomic regions as the most severely affected bones.

Question 300

Topic: 10. Pathology and Oncology

A 60-year-old female undergoes prophylactic fixation for an impending pathologic fracture of the femur secondary to metastatic thyroid carcinoma. Which of the following describes the classic radiographic appearance of this lesion?

. Purely blastic and sclerotic
. Mixed blastic and lytic
. Purely lytic and highly vascular
. Permeative with an onion-skin reaction
. Ground-glass matrix

Correct Answer & Explanation

. Purely lytic and highly vascular

Explanation

Bone metastases arising from thyroid and renal cell carcinomas are classically purely osteolytic, destructive, and notoriously hypervascular. Pre-operative embolization is routinely recommended before surgical stabilization to mitigate catastrophic intraoperative blood loss.

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