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10. Pathology and Oncology MCQs

Practice Set 341 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 6801

Topic: Bone Tumors

A 9-year-old boy presents with multiple bony protuberances, sparse hair, a bulbous nose, and mild intellectual disability. Radiographs confirm multiple hereditary exostoses (osteochondromas). Which of the following chromosomal microdeletions is responsible for this specific syndrome?

. 15q11-q13
. 22q11.2
. 8q24.1
. 5p15.2
. 4p16.3

Correct Answer & Explanation

. 8q24.1

Explanation

The patient has Langer-Giedion syndrome (TRPS Type II). It is caused by a contiguous gene deletion syndrome at chromosome 8q24.1 that encompasses both the TRPS1 gene (causing TRPS features) and the EXT1 gene (causing multiple osteochondromas).

Question 6802

Topic: Bone Tumors

A 45-year-old male presents with recurrent non-union of a transverse femur fracture. Radiographs show diffusely thickened cortices and an obliterated medullary canal. History reveals he suffers from frequent sinus infections and has a sibling with similar skeletal findings. What hematologic complication is most likely to develop in this patient?

. Polycythemia vera
. Myelophthisic anemia and extramedullary hematopoiesis
. Acute lymphoblastic leukemia
. Hemophilia A
. Multiple myeloma

Correct Answer & Explanation

. Myelophthisic anemia and extramedullary hematopoiesis

Explanation

The patient has osteopetrosis. Because the osteoclasts fail to resorb bone, the medullary cavity is obliterated by unresorbed primary spongiosa, leading to myelophthisis (marrow failure), pancytopenia, and secondary extramedullary hematopoiesis (hepatosplenomegaly).

Question 6803

Topic: Bone Tumors

What is the most common secondary malignancy arising in a patient with long-standing Paget's disease of bone?

. Chondrosarcoma
. Osteosarcoma
. Multiple myeloma
. Ewing sarcoma
. Fibrosarcoma

Correct Answer & Explanation

. Osteosarcoma

Explanation

Osteosarcoma is the most common secondary malignancy in Paget's disease, occurring in approximately 1% of patients. It typically presents with new, severe pain and cortical destruction.

Question 6804

Topic: 10. Pathology and Oncology

A 25-year-old male presents with recurrent fractures and mild anemia. Radiographs show diffusely dense bones with a 'bone within a bone' appearance in the pelvis and spine.

What is the typical inheritance pattern of this specific variant of the disorder?

. Autosomal recessive
. Autosomal dominant
. X-linked recessive
. X-linked dominant
. Mitochondrial

Correct Answer & Explanation

. Autosomal dominant

Explanation

Adult (benign) osteopetrosis, also known as Albers-Schonberg disease, is typically inherited in an autosomal dominant pattern. It presents later in life with milder symptoms compared to the fatal infantile recessive form.

Question 6805

Topic: Bone Tumors

TRPS type II (Langer-Giedion syndrome) differs from TRPS type I by the presence of which of the following additional skeletal manifestations?

. Multiple osteochondromas
. Osteopoikilosis
. Fibrous dysplasia
. Enchondromatosis
. Melorheostosis

Correct Answer & Explanation

. Multiple osteochondromas

Explanation

TRPS type II involves a contiguous gene deletion affecting both the TRPS1 and EXT1 genes. The deletion of EXT1 leads to the development of multiple hereditary exostoses (osteochondromas).

Question 6806

Topic: Bone Tumors

A 10-year-old boy presents with sparse hair, a bulbous nose, and multiple bony exostoses on his long bones. Hand radiographs show cone-shaped epiphyses. This specific syndrome (Langer-Giedion syndrome) is caused by a contiguous gene deletion involving TRPS1 and which other gene?

. EXT1
. EXT2
. TCIRG1
. SQSTM1
. CLCN7

Correct Answer & Explanation

. EXT1

Explanation

Langer-Giedion syndrome (TRPS Type II) is a contiguous gene syndrome caused by the deletion of both the TRPS1 gene and the EXT1 gene on chromosome 8q24. This explains the combination of Trichorhinophalangeal features and multiple osteochondromas.

Question 6807

Topic: 10. Pathology and Oncology

A 72-year-old man with long-standing Paget's disease presents with a new onset of severe, unremitting thigh pain and a palpable mass. Radiographs show aggressive cortical destruction and a soft tissue extension.

What is the most likely diagnosis?

. Pagetic stress fracture
. Secondary chondrosarcoma
. Secondary osteosarcoma
. Metastatic prostate carcinoma
. Osteomyelitis

Correct Answer & Explanation

. Secondary osteosarcoma

Explanation

Secondary osteosarcoma is a rare but highly lethal complication of Paget's disease, occurring in about 1% of patients. It typically presents with new, severe pain and destructive radiographic changes in a previously affected bone.

Question 6808

Topic: 10. Pathology and Oncology

A 35-year-old woman is incidentally found to have 'sandwich vertebrae' on a lateral spine radiograph.

Which of the following describes the most likely inheritance pattern and prognosis of her condition?

. Autosomal recessive, usually fatal in early childhood without transplant
. Autosomal dominant, relatively benign course with normal life expectancy
. X-linked recessive, progressive severe limb deformities
. Mitochondrial inheritance, associated with severe myopathy
. Sporadic mutation, high risk of malignant transformation

Correct Answer & Explanation

. Autosomal dominant, relatively benign course with normal life expectancy

Explanation

Adult-onset osteopetrosis (Albers-Schonberg disease) is typically autosomal dominant and has a relatively benign course. Radiographically, it is characterized by dense bands of sclerosis at the vertebral endplates, known as 'sandwich vertebrae'.

Question 6809

Topic: 10. Pathology and Oncology

A 72-year-old male with known Paget's disease presents with a sudden increase in severe, unremitting right thigh pain and swelling. Radiographs show a destructive lytic lesion with cortical breakthrough in a previously thickened, bowed femur.

What is the most likely diagnosis?

. Metastatic prostate cancer
. Pagetic insufficiency fracture
. Secondary osteosarcoma
. Primary chondrosarcoma
. Multiple myeloma

Correct Answer & Explanation

. Secondary osteosarcoma

Explanation

Sudden onset of severe pain, swelling, and a destructive lytic lesion in a patient with Paget's disease is highly suspicious for malignant transformation to secondary osteosarcoma. This dreaded complication occurs in approximately 1% of patients and carries a poor prognosis.

Question 6810

Topic: 10. Pathology and Oncology

An infant with failure to thrive is diagnosed with autosomal recessive malignant osteopetrosis. On physical exam, the infant's abdomen is notably protuberant and firm. The abdominal distension in this patient is primarily related to which of the following pathophysiologic processes?

. Splenic sequestration of defective erythrocytes
. Extramedullary hematopoiesis due to marrow space obliteration
. Hepatic failure secondary to iron overload
. Ascites from portal hypertension
. Mesenteric lymphadenopathy from recurrent infections

Correct Answer & Explanation

. Extramedullary hematopoiesis due to marrow space obliteration

Explanation

In malignant infantile osteopetrosis, defective osteoclast function leads to the failure of medullary canal formation, resulting in bone marrow obliteration. This forces profound extramedullary hematopoiesis in the liver and spleen, presenting clinically as massive hepatosplenomegaly.

Question 6811

Topic: 10. Pathology and Oncology

A 55-year-old male presents with a large, deep-seated painless mass in his thigh. MRI shows a predominantly lipomatous tumor with thickened septa. Histopathology shows mature adipocytes with focal nuclear atypia.

Which genetic alteration is most specific to confirm the diagnosis of an atypical lipomatous tumor?

. t(X;18) translocation
. MDM2 gene amplification
. t(12;16) translocation
. GNAS mutation
. TRK fusion

Correct Answer & Explanation

. MDM2 gene amplification

Explanation

Atypical lipomatous tumors (well-differentiated liposarcomas) are characterized by ring or giant rod chromosomes leading to MDM2 and CDK4 gene amplification on chromosome 12q13-15. Testing for MDM2 amplification distinguishes it from a benign lipoma.

Question 6812

Topic: 10. Pathology and Oncology

A 28-year-old male with Multiple Hereditary Exostoses presents with recent growth and pain in a distal femur lesion. MRI shows a cartilage cap thickness of 25 mm.

What is the most likely pathological finding in this growing lesion?

. Secondary osteosarcoma
. Secondary chondrosarcoma
. Benign proliferation of the physis
. Fibrous dysplasia
. Clear cell chondrosarcoma

Correct Answer & Explanation

. Secondary chondrosarcoma

Explanation

Malignant transformation of an osteochondroma is almost exclusively to a secondary chondrosarcoma. A cartilage cap thickness greater than 2 cm (20 mm) in an adult is highly suspicious for malignant transformation.

Question 6813

Topic: 10. Pathology and Oncology

A 45-year-old male presents with chronic knee pain, catching, and restricted range of motion. Radiographs reveal multiple uniform, calcified intra-articular loose bodies.

Primary synovial chondromatosis is currently best described as:

. A degenerative process secondary to osteoarthritis
. A benign neoplasm driven by FN1-ACVR2A fusions
. An inflammatory arthropathy associated with HLA-B27
. A reactive metaplasia with no genetic alteration
. A malignant precursor lesion requiring amputation

Correct Answer & Explanation

. A benign neoplasm driven by FN1-ACVR2A fusions

Explanation

Primary synovial chondromatosis was historically considered a reactive metaplasia. However, cytogenetic studies identifying recurrent FN1-ACVR2A fusions have reclassified it as a benign neoplastic process.

Question 6814

Topic: Soft Tissue Tumors & Metastasis

Deep lipomas of the extremities are classified as intramuscular or intermuscular. Which of the following statements regarding intramuscular lipomas is true compared to their subcutaneous counterparts?

. They have a higher rate of local recurrence after marginal excision
. They are uniformly associated with MDM2 amplification
. They do not infiltrate between skeletal muscle fibers
. They undergo malignant transformation to liposarcoma in 20% of cases
. They present with intense nocturnal pain responsive to NSAIDs

Correct Answer & Explanation

. They have a higher rate of local recurrence after marginal excision

Explanation

Intramuscular lipomas frequently infiltrate between muscle fibers, making complete enucleation more difficult. This leads to a higher local recurrence rate (up to 15%) compared to well-encapsulated subcutaneous lipomas.

Question 6815

Topic: 10. Pathology and Oncology

An atypical lipomatous tumor (well-differentiated liposarcoma) located in which of the following anatomic areas carries the highest risk for disease-specific mortality and dedifferentiation?

. Subcutaneous tissue of the thigh
. Intramuscular compartment of the deltoid
. Retroperitoneum
. Subcutaneous tissue of the back
. Intermuscular space of the calf

Correct Answer & Explanation

. Retroperitoneum

Explanation

Lesions in the retroperitoneum carry a much worse prognosis because complete surgical margins are difficult to achieve. The high rate of local recurrence in the retroperitoneum increases the time-dependent risk of dedifferentiation.

Question 6816

Topic: Bone Tumors

An 18-year-old presents with a painless mass at the proximal medial tibia.

Which of the following radiographic or MRI findings is the absolute sine qua non for diagnosing a true osteochondroma?

. A calcified cartilage cap exceeding 3 cm
. Periosteal reaction with a Codman triangle
. Continuity of the medullary cavity and cortex of the lesion with the host bone
. A radiolucent nidus surrounded by reactive sclerosis
. Invasion of the adjacent neurovascular bundle

Correct Answer & Explanation

. Continuity of the medullary cavity and cortex of the lesion with the host bone

Explanation

The pathognomonic imaging feature of an osteochondroma is direct cortico-medullary continuity with the native host bone. This helps differentiate it from surface lesions like parosteal osteosarcoma.

Question 6817

Topic: 10. Pathology and Oncology

A 55-year-old male presents with a deep, painless, slow-growing mass in his thigh.

Biopsy reveals mature adipocytes with focal nuclear atypia. To differentiate an atypical lipomatous tumor from a benign lipoma, which molecular finding is most diagnostic?

. MDM2 and CDK4 amplification
. t(X;18) translocation
. t(12;16) translocation
. c-myc amplification
. t(11;22) translocation

Correct Answer & Explanation

. MDM2 and CDK4 amplification

Explanation

Atypical lipomatous tumors (well-differentiated liposarcomas) are characterized by ring or giant marker chromosomes that result in the amplification of MDM2 and CDK4 genes. Benign lipomas lack this genetic amplification.

Question 6818

Topic: 10. Pathology and Oncology

A 25-year-old male with Multiple Hereditary Exostoses (MHE) reports rapid growth of a previously stable mass on his proximal tibia.

MRI is obtained. Which of the following MRI findings is the most concerning indicator of malignant transformation to secondary chondrosarcoma?

. Medullary continuity with the host bone
. A cartilage cap thickness greater than 2.0 cm
. Edema in the adjacent vastus medialis muscle
. Enchondral ossification at the base of the stalk
. A pedunculated morphology

Correct Answer & Explanation

. A cartilage cap thickness greater than 2.0 cm

Explanation

In a skeletally mature patient, a cartilage cap thickness exceeding 1.5 to 2.0 cm on MRI is highly suspicious for malignant transformation to secondary chondrosarcoma. Medullary continuity is a diagnostic feature of a benign osteochondroma, not a sign of malignancy.

Question 6819

Topic: 10. Pathology and Oncology

A 40-year-old male presents with chronic knee catching and swelling. Imaging shows multiple intra-articular calcific loose bodies.

Which histopathologic feature most reliably differentiates primary synovial chondromatosis from secondary osteochondromatosis?

. Uniform size of nodules with concentric rings of ossification
. Synovial chondroid metaplasia with cellular atypia and binucleated cells
. Presence of cholesterol crystals in the stroma
. A distinct lack of synovial lining hyperplasia
. Extensive invasion into the underlying subchondral bone

Correct Answer & Explanation

. Synovial chondroid metaplasia with cellular atypia and binucleated cells

Explanation

Primary synovial chondromatosis represents benign neoplastic metaplasia of the synovium, characterized by clustering of chondrocytes and cellular atypia (which can mimic chondrosarcoma). Secondary chondromatosis bodies simply represent detached articular fragments and lack this metaplastic atypia.

Question 6820

Topic: 10. Pathology and Oncology

Which of the following MRI sequences is most useful for confirming that a well-circumscribed soft tissue mass is a benign lipoma rather than a fluid-filled cyst?

. T2-weighted sequence without fat saturation
. T1-weighted fat-suppressed sequence
. Gradient echo (GRE) sequence
. Short tau inversion recovery (STIR)
. T1-weighted sequence with gadolinium contrast

Correct Answer & Explanation

. T1-weighted fat-suppressed sequence

Explanation

Both fat and proteinaceous fluid/hemorrhage can appear bright on standard T1-weighted images. A T1-weighted fat-suppressed sequence will show a drop in signal for a lipoma, definitively identifying it as fat.

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