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10. Pathology and Oncology MCQs

Practice Set 149 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 2961

Topic: 10. Pathology and Oncology

A 35-year-old male presents with a slowly enlarging, painful mass around his right ankle. MRI demonstrates a deep, well-circumscribed soft tissue mass adjacent to the joint capsule but not extending into the joint space. Histopathologic examination of a core needle biopsy reveals a biphasic pattern consisting of both uniform spindle cells and epithelial cells forming glandular structures. Which of the following is the characteristic chromosomal translocation associated with this diagnosis?

. t(11;22)(q24;q12)
. t(12;16)(q13;p11)
. t(X;18)(p11;q11)
. t(2;13)(q35;q14)
. t(9;22)(q22;q12)

Correct Answer & Explanation

. t(X;18)(p11;q11)

Explanation

The clinical presentation and biphasic histologic pattern (spindle and epithelial cells) are classic for synovial sarcoma. Despite its name, synovial sarcoma rarely originates from the intra-articular synovium, typically arising in soft tissues near large joints. It is molecularly characterized by the t(X;18)(p11;q11) translocation, which results in the SYT-SSX fusion gene. This translocation is present in over 90% of cases and serves as a diagnostic hallmark. t(11;22) is associated with Ewing sarcoma, t(12;16) with myxoid liposarcoma, t(2;13) with alveolar rhabdomyosarcoma, and t(9;22) with extraskeletal myxoid chondrosarcoma.

Question 2962

Topic: 10. Pathology and Oncology
A 15-year-old boy presents with severe progressive knee pain and localized swelling over the past two months. Radiographs reveal a destructive, mixed lytic and sclerotic lesion in the distal femoral metaphysis with an associated Codman triangle periosteal reaction. Core needle biopsy confirms high-grade intramedullary osteosarcoma. Following staging, the patient undergoes 10 weeks of neoadjuvant chemotherapy followed by surgical resection. Which of the following factors is considered the most reliable independent prognostic indicator of overall long-term survival in this patient?
. Initial tumor volume on MRI
. Presence of 'skip' metastases on preoperative MRI
. Histologic percentage of tumor necrosis in the resected specimen
. Pretreatment serum alkaline phosphatase level
. Specific histologic variant (e.g., osteoblastic vs. chondroblastic)

Correct Answer & Explanation

. Histologic percentage of tumor necrosis in the resected specimen

Explanation

In patients with high-grade conventional osteosarcoma, the histologic response to neoadjuvant chemotherapy—measured by the percentage of tumor necrosis in the surgically resected specimen—is the most powerful and reliable predictor of overall survival. A 'good response' is typically defined as ≥ 90% tumor necrosis and is associated with significantly improved long-term survival rates compared to a 'poor response' (< 90% necrosis). While tumor size, skip metastases, and elevated alkaline phosphatase levels do carry prognostic significance, the degree of chemotherapy-induced necrosis remains the most validated prognostic indicator.

Question 2963

Topic: 10. Pathology and Oncology

A 10-year-old girl is brought to the clinic with persistent thigh pain and a low-grade fever. Radiographs of the femur demonstrate a permeative lytic lesion in the diaphysis with an 'onion skin' periosteal reaction. A core biopsy reveals sheets of uniform, small round blue cells with scant cytoplasm. Immunohistochemical staining of the biopsy specimen will most likely show strong, diffuse membranous positivity for which of the following markers?

. CD99 (MIC2)
. S-100 protein
. Desmin
. Cytokeratin
. MyoD1

Correct Answer & Explanation

. CD99 (MIC2)

Explanation

The clinical presentation, diaphyseal location, 'onion skin' (lamellated) periosteal reaction, and small round blue cell histology are highly characteristic of Ewing sarcoma. Immunohistochemically, Ewing sarcoma classically exhibits strong, diffuse membranous staining for CD99 (also known as MIC2). This tumor is genetically defined by the t(11;22) translocation yielding the EWSR1-FLI1 fusion. S-100 is typically positive in neural crest tumors (e.g., schwannoma, melanoma) and cartilaginous tumors. Desmin and MyoD1 are markers for skeletal muscle differentiation (e.g., rhabdomyosarcoma). Cytokeratin is a marker for epithelial differentiation (carcinomas) and synovial sarcoma.

Question 2964

Topic: 10. Pathology and Oncology

A 12-year-old boy presents with a painful mass in his distal femur. Biopsy confirms conventional high-grade osteosarcoma. Which of the following genetic syndromes is associated with a germline mutation in the RECQL4 helicase gene and a significantly increased risk of developing this malignancy?

. Li-Fraumeni syndrome
. Rothmund-Thomson syndrome
. Hereditary Retinoblastoma
. Multiple Hereditary Exostoses
. McCune-Albright syndrome

Correct Answer & Explanation

. Rothmund-Thomson syndrome

Explanation

Rothmund-Thomson syndrome is an autosomal recessive disorder caused by a RECQL4 mutation, predisposing patients to osteosarcoma. Li-Fraumeni is associated with p53 mutations, while Hereditary Retinoblastoma involves the Rb1 gene.

Question 2965

Topic: Bone Tumors



Fibrous dysplasia is a benign fibro-osseous bone lesion that can present as a solitary lesion or as part of a more complex syndrome. This condition is fundamentally caused by a somatic activating mutation in which of the following genes?

. GNAS
. EXT1
. RB1
. FGFR3
. COL1A1

Correct Answer & Explanation

. GNAS

Explanation

Fibrous dysplasia results from a somatic activating missense mutation in the GNAS gene, which leads to constitutive activation of Gs-alpha and overproduction of intracellular cAMP. When associated with cafe-au-lait macules and precocious puberty, it is termed McCune-Albright syndrome.

Question 2966

Topic: 10. Pathology and Oncology

A 15-year-old boy presents with a permeative lytic lesion in the diaphysis of the femur with a periosteal "onion-skin" reaction. Biopsy reveals uniform small round blue cells. Which chromosomal translocation is most characteristic of this tumor?

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

Correct Answer & Explanation

. t(11;22)

Explanation

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

Question 2967

Topic: 10. Pathology and Oncology

A 14-year-old girl is diagnosed with conventional osteosarcoma of the distal femur. A mutation in which of the following tumor suppressor genes is most commonly implicated in the pathogenesis of this disease?

. BRCA1
. p53
. APC
. NF1
. EXT1

Correct Answer & Explanation

. p53

Explanation

Mutations in the TP53 (p53) tumor suppressor gene (as seen in Li-Fraumeni syndrome) and the RB1 (retinoblastoma) gene are the most frequently implicated genetic abnormalities in the development of osteosarcoma.

Question 2968

Topic: 10. Pathology and Oncology

A 30-year-old man presents with a slowly enlarging, deep soft-tissue mass near his knee. A core needle biopsy reveals a biphasic tumor consisting of epithelial and spindle cell components. Which of the following chromosomal translocations is highly specific for this diagnosis?

. t(11;22) (q24;q12)
. t(X;18) (p11;q11)
. t(12;16) (q13;p11)
. t(9;22) (q22;q12)
. t(2;13) (q35;q14)

Correct Answer & Explanation

. t(X;18) (p11;q11)

Explanation

The clinical presentation and biphasic histology indicate a synovial sarcoma. This tumor is characterized by the t(X;18) translocation, which results in the SYT-SSX fusion gene.

Question 2969

Topic: 10. Pathology and Oncology

A 24-year-old man complains of a dull ache in his lower back that is minimally relieved by NSAIDs. Radiographs show a 2.5-cm radiolucent lesion with surrounding sclerosis in the posterior elements of L4. Histology reveals disorganized osteoid surrounded by osteoblasts without malignant features. What is the most likely diagnosis?

. Osteoid osteoma
. Osteoblastoma
. Aneurysmal bone cyst
. Giant cell tumor
. Chondroblastoma

Correct Answer & Explanation

. Osteoblastoma

Explanation

Osteoblastomas are histologically identical to osteoid osteomas but are distinguished by being larger than 2 cm. They also tend to be less responsive to NSAIDs and have a predilection for the posterior elements of the spine.

Question 2970

Topic: 10. Pathology and Oncology

A 9-year-old boy presents with a painful diaphyseal femur lesion showing an "onion skin" periosteal reaction. Biopsy reveals sheets of uniform small round blue cells. Immunohistochemical staining is typically positive for which of the following markers?

. Cytokeratin
. CD99 (MIC2)
. S-100
. Desmin
. Myogenin

Correct Answer & Explanation

. CD99 (MIC2)

Explanation

The presentation is classic for Ewing sarcoma, which is driven by the t(11;22) translocation. These tumors are characteristically highly positive for the CD99 cell surface glycoprotein.

Question 2971

Topic: 10. Pathology and Oncology

A 55-year-old man presents with worsening shoulder pain. Radiographs reveal a large destructive lesion in the proximal humerus with intralesional "popcorn" calcifications and endosteal scalloping greater than two-thirds of the cortical thickness. The most appropriate initial definitive treatment is:

. Intralesional curettage and bone grafting
. Wide surgical resection
. Neoadjuvant chemotherapy followed by limb salvage
. Primary radiation therapy
. Radiofrequency ablation

Correct Answer & Explanation

. Wide surgical resection

Explanation

The clinical and radiographic findings are highly characteristic of an intermediate- to high-grade chondrosarcoma. Because these tumors are generally resistant to chemotherapy and radiation, the mainstay of treatment is wide surgical resection.

Question 2972

Topic: Bone Tumors

A 65-year-old woman presents with diffuse skeletal pain and a pathological fracture of the proximal femur. Laboratories reveal anemia, hypercalcemia, and an elevated M-spike on serum protein electrophoresis. Which of the following radiographic findings is most characteristic of her condition?

. Punched-out lytic lesions without reactive sclerosis
. Dense blastic lesions of the axial skeleton
. Extensive periosteal "sunburst" reaction
. Epiphyseal lytic lesions with a sclerotic rim
. Ground-glass matrix in the medullary canal

Correct Answer & Explanation

. Punched-out lytic lesions without reactive sclerosis

Explanation

Multiple myeloma is a plasma cell dyscrasia characterized radiographically by sharply demarcated, "punched-out" lytic lesions with no surrounding reactive bone sclerosis. This is due to profound osteoclast activation and osteoblast inhibition.

Question 2973

Topic: 10. Pathology and Oncology

A 62-year-old man presents with chronic lower back pain and bowel incontinence. Radiographs demonstrate a destructive lesion involving the sacrum. Biopsy reveals physaliferous cells in a myxoid background. Which of the following immunohistochemical markers is most specific for confirming this diagnosis?

. S-100
. CD99
. Brachyury
. MUC4
. MDM2

Correct Answer & Explanation

. Brachyury

Explanation

Chordomas are locally aggressive malignant tumors arising from notochordal remnants. They uniquely stain positive for Brachyury, a transcription factor, which distinguishes them from chondrosarcomas.

Question 2974

Topic: 10. Pathology and Oncology

A 12-year-old girl presents with a pathologic fracture of her proximal femur. Radiographs reveal a "ground-glass" appearance of the lesion with coxa vara deformity. A biopsy confirms fibrous dysplasia. Which of the following best describes the underlying pathophysiology of this condition?

. Translocation t(11;22)
. Mutation in the EXT1 gene causing defective heparan sulfate synthesis
. Activating missense mutation in the GNAS gene
. Defect in the TCIRG1 gene affecting osteoclast ruffled borders
. Mutation in the SQSTM1 gene

Correct Answer & Explanation

. Activating missense mutation in the GNAS gene

Explanation

Fibrous dysplasia results from an activating somatic mutation in the GNAS gene, which encodes the alpha subunit of the Gs stimulatory protein. This leads to increased intracellular cAMP and abnormal osteoblast differentiation.

Question 2975

Topic: 10. Pathology and Oncology

A 15-year-old boy develops a highly malignant bone forming tumor in the distal femur. His medical history is significant for bilateral retinoblastoma treated during infancy. Loss of heterozygosity or mutation in which of the following genes most directly predisposes him to this skeletal malignancy?

. TP53
. RB1
. PTEN
. NF1
. APC

Correct Answer & Explanation

. RB1

Explanation

Patients with hereditary retinoblastoma have a germline mutation in the RB1 tumor suppressor gene. This significantly increases their lifetime risk of developing secondary primary malignancies, most notably osteosarcoma.

Question 2976

Topic: 10. Pathology and Oncology

A 28-year-old man presents with a slow-growing, painful mass near his knee joint. MRI shows a soft-tissue mass adjacent to but not within the joint space. Core needle biopsy reveals a biphasic tumor with both epithelial and spindle cell components. Which of the following chromosomal translocations is characteristic of this lesion?

. t(X;18)(p11;q11)
. t(11;22)(q24;q12)
. t(12;16)(q13;p11)
. t(2;13)(q35;q14)
. t(9;22)(q22;q12)

Correct Answer & Explanation

. t(X;18)(p11;q11)

Explanation

Synovial sarcoma is characterized by the t(X;18)(p11;q11) translocation, which fuses the SYT gene on chromosome 18 with SSX1, SSX2, or SSX4 on the X chromosome. This genetic fusion is diagnostic.

Question 2977

Topic: 10. Pathology and Oncology

A 68-year-old woman presents with severe back pain and fatigue. Laboratory investigations reveal hypercalcemia, normocytic anemia, and an elevated serum creatinine. Radiographs of the skull demonstrate multiple "punched-out" radiolucent lesions without sclerotic borders. Which of the following tests is most appropriate to confirm the underlying diagnosis?

. Serum prostate-specific antigen (PSA)
. Flow cytometry for CD99
. Serum and urine protein electrophoresis
. Bone marrow biopsy evaluating for t(11;22)
. Thyroid-stimulating hormone (TSH) level

Correct Answer & Explanation

. Serum and urine protein electrophoresis

Explanation

The clinical presentation of hypercalcemia, renal failure, anemia, and punched-out lytic bone lesions is classic for Multiple Myeloma (CRAB criteria). Serum and urine protein electrophoresis (SPEP/UPEP) with immunofixation are essential to detect the characteristic monoclonal protein spike.

Question 2978

Topic: 10. Pathology and Oncology

A 10-year-old girl presents with a rapidly expanding, painful lesion of the proximal humerus. Radiographs show an eccentrically located, expansile, lytic lesion. Biopsy reveals blood-filled spaces lacking an endothelial lining and interspersed with multinucleated giant cells. Which of the following genetic abnormalities is considered the primary driver of this lesion?

. GNAS mutation
. H3F3A mutation
. USP6 translocation
. EXT1 mutation
. TP53 mutation

Correct Answer & Explanation

. USP6 translocation

Explanation

Primary Aneurysmal Bone Cysts (ABCs) are now recognized as true neoplasms driven by translocations involving the USP6 gene on chromosome 17p13. This distinguishes primary ABCs from secondary ABCs which occur within other tumors.

Question 2979

Topic: 10. Pathology and Oncology

A 15-year-old boy presents with right knee pain. Imaging reveals a destructive, mixed lytic and sclerotic lesion in the distal femoral metaphysis with a periosteal sunburst reaction. Biopsy confirms high-grade intramedullary osteosarcoma. Which of the following genetic syndromes is most strongly associated with an increased risk of developing this specific malignancy?

. Neurofibromatosis type 1
. Li-Fraumeni syndrome
. McCune-Albright syndrome
. Multiple Hereditary Exostoses
. Marfan syndrome

Correct Answer & Explanation

. Li-Fraumeni syndrome

Explanation

Li-Fraumeni syndrome is an autosomal dominant disorder caused by a germline mutation in the TP53 tumor suppressor gene and is strongly associated with osteosarcoma. Other known associations for osteosarcoma include familial retinoblastoma (RB1 mutation) and Rothmund-Thomson syndrome.

Question 2980

Topic: Bone Tumors

A 19-year-old man complains of localized right tibial pain that is worse at night and dramatically relieved by NSAIDs.

Imaging reveals a small radiolucent nidus surrounded by dense reactive sclerosis. The dramatic pain relief provided by NSAIDs in this condition is due to the local inhibition of which of the following?

. Substance P
. Prostaglandin E2
. Interleukin-1
. Tumor Necrosis Factor-alpha
. Bradykinin

Correct Answer & Explanation

. Prostaglandin E2

Explanation

Osteoid osteomas uniquely secrete high levels of Prostaglandin E2 (PGE2) due to increased cyclooxygenase (COX) expression within the nidus. NSAIDs inhibit COX, effectively reducing PGE2 levels and providing the characteristic dramatic pain relief.

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