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10. Pathology and Oncology MCQs

Practice Set 307 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 6121

Topic: Bone Tumors

A 14-year-old girl with polyostotic fibrous dysplasia presents with increasing groin and thigh pain. Radiographs demonstrate a progressive shepherd's crook deformity of the proximal femur with an impending fracture. What is the most appropriate surgical management?

. Curettage and cancellous bone grafting of the lesion
. Valgus-producing proximal femoral osteotomy with intramedullary nailing
. Varus-producing proximal femoral osteotomy with blade plate fixation
. Prophylactic external beam radiation therapy
. Observation in a hip spica cast

Correct Answer & Explanation

. Valgus-producing proximal femoral osteotomy with intramedullary nailing

Explanation

The shepherd's crook deformity in fibrous dysplasia leads to high mechanical stress on the proximal femur. Treatment requires a valgus-producing osteotomy to correct the mechanical axis, combined with intramedullary nailing spanning the entire bone to prevent stress risers and future fractures.

Question 6122

Topic: 10. Pathology and Oncology

Primary synovial chondromatosis can occasionally mimic chondrosarcoma on histological evaluation. Which of the following microscopic features is commonly found in primary synovial chondromatosis but should NOT lead to an automatic diagnosis of malignancy in this specific context?

. Atypical hypercellularity and binucleated chondrocytes
. Invasion into the local neurovascular bundles
. Extensive malignant osteoid production
. Cortical bone destruction with a permeative pattern
. High mitotic rate with atypical mitotic figures

Correct Answer & Explanation

. Atypical hypercellularity and binucleated chondrocytes

Explanation

Primary synovial chondromatosis typically demonstrates hypercellularity, pleomorphism, and binucleated cells, which can easily be mistaken for low-grade chondrosarcoma. However, in the absence of frank tissue invasion or atypical mitoses, these features are considered benign in this entity.

Question 6123

Topic: 10. Pathology and Oncology

A 15-year-old boy presents with knee pain. Radiographs reveal an expansile, eccentric lytic lesion in the distal femur. Core needle biopsy shows multiple blood-filled spaces separated by fibrous septa containing giant cells. Which genetic translocation is highly specific for this primary lesion?

. t(11;22)
. t(X;18)
. t(16;17)
. t(12;16)
. t(9;22)

Correct Answer & Explanation

. t(16;17)

Explanation

The lesion is an aneurysmal bone cyst (ABC). Primary ABCs are neoplasms driven by a specific t(16;17) translocation that results in the upregulation of the USP6 oncogene.

Question 6124

Topic: 10. Pathology and Oncology

An 18-year-old male presents with a rapidly expanding lytic lesion in the proximal tibia. MRI demonstrates fluid-fluid levels. Core biopsy is performed to differentiate an aneurysmal bone cyst (ABC) from a telangiectatic osteosarcoma. Which histologic feature most reliably confirms the diagnosis of telangiectatic osteosarcoma over an ABC?

. Presence of fluid-fluid levels on gross pathology
. Cellular atypia and malignant osteoid within the septa
. Abundant multinucleated giant cells
. Hemosiderin-laden macrophages
. Reactive woven bone formation with osteoblastic rimming

Correct Answer & Explanation

. Cellular atypia and malignant osteoid within the septa

Explanation

Both ABCs and telangiectatic osteosarcomas present with cystic spaces and fluid-fluid levels. However, telangiectatic osteosarcoma is distinguished by the presence of highly atypical, malignant cells producing malignant osteoid within the septa separating the blood-filled spaces.

Question 6125

Topic: Bone Tumors
A 6-year-old girl is evaluated for a limp, precocious puberty, and large café-au-lait spots with irregular 'coast of Maine' borders. Pelvic radiographs show a bubbly, expansile lesion in the proximal femur with a ground-glass matrix. The somatic mosaic mutation responsible for this syndrome causes hyperactivation of which pathway?
. cAMP secondary messenger system (G-protein)
. Fibroblast growth factor receptor 3
. Cartilage oligomeric matrix protein
. Membrane sulfate transporter
. Wnt/beta-catenin signaling

Correct Answer & Explanation

. cAMP secondary messenger system (G-protein)

Explanation

McCune-Albright syndrome consists of polyostotic fibrous dysplasia, precocious puberty, and café-au-lait spots. It is caused by a somatic mutation in the GNAS gene, which leads to constitutive activation of the Gs-alpha protein and continuous cAMP production.

Question 6126

Topic: Bone Tumors

A 12-year-old girl undergoes extended intralesional curettage, high-speed burring, and phenol adjuvant therapy for an aneurysmal bone cyst of the distal tibia. Despite adequate initial surgery, the lesion recurs 1 year later without soft tissue extension. What is the next most appropriate step in management?

. Below-knee amputation
. External beam radiation therapy
. Repeat extended curettage with adjuvant therapy and bone grafting
. Systemic neo-adjuvant chemotherapy
. Wide en bloc resection of the distal tibia

Correct Answer & Explanation

. Repeat extended curettage with adjuvant therapy and bone grafting

Explanation

Aneurysmal bone cysts have a recurrence rate of 10-20% even with modern curettage techniques. The standard treatment for a local, contained recurrence remains repeat extended intralesional curettage with local adjuvant therapy (e.g., phenol, cryotherapy, or argon beam) and grafting.

Question 6127

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with a painful, swollen thigh. Radiographs demonstrate a permeative, diaphyseal lytic lesion with an 'onion-skin' periosteal reaction. A biopsy confirms Ewing sarcoma. Which of the following chromosomal translocations is most characteristic of this tumor?

. t(11;22) EWS-FLI1
. t(X;18) SYT-SSX1
. t(2;13) PAX3-FKHR
. t(12;16) FUS-CHOP
. t(9;22) BCR-ABL

Correct Answer & Explanation

. t(11;22) EWS-FLI1

Explanation

Ewing sarcoma is classically associated with the t(11;22) chromosomal translocation, resulting in the EWS-FLI1 fusion protein. This is present in approximately 85% of cases.

Question 6128

Topic: 10. Pathology and Oncology

A 70-year-old male with long-standing Paget disease of bone complains of a sudden increase in pain and swelling in his right proximal femur over the last two months. Radiographs reveal a new, destructive lytic lesion with cortical breakthrough. What is the most likely diagnosis?

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

Correct Answer & Explanation

. Osteosarcoma

Explanation

Secondary osteosarcoma is the most common malignant transformation seen in patients with Paget disease of bone. It occurs in about 1% of patients and portends a very poor prognosis.

Question 6129

Topic: 10. Pathology and Oncology

A 40-year-old female presents with a swelling in her knee joint. MRI reveals a large joint effusion with synovial hypertrophy demonstrating 'blooming artifact' on gradient-echo sequences. Biopsy confirms pigmented villonodular synovitis (PVNS/TGCT). What is the specific genetic aberration driving the overproliferation of cells in this condition?

. GNAS mutation
. CSF1 translocation t(1;2)
. p53 mutation
. FGFR3 mutation
. RUNX2 mutation

Correct Answer & Explanation

. CSF1 translocation t(1;2)

Explanation

Pigmented villonodular synovitis (PVNS), or tenosynovial giant cell tumor (TGCT), is driven by a t(1;2) translocation involving the CSF1 gene. This leads to an overexpression of CSF-1, which recruits a large inflammatory infiltrate of macrophages.

Question 6130

Topic: 10. Pathology and Oncology

Which of the following criteria is NOT part of the Mirels' scoring system for predicting the risk of a pathologic fracture in a long bone?

. Site of the lesion
. Size of the lesion relative to bone diameter
. Nature of the lesion (blastic, mixed, lytic)
. Patient age and gender
. Presence and severity of pain

Correct Answer & Explanation

. Patient age and gender

Explanation

The Mirels' scoring system includes four categories: Site (upper limb, lower limb, peritrochanteric), Size (<1/3, 1/3-2/3, >2/3 cortical diameter), Nature (blastic, mixed, lytic), and Pain (mild, moderate, functional). Age and gender are not included.

Question 6131

Topic: 10. Pathology and Oncology

A 15-year-old male presents with bone pain and a palpable mass in his distal femur. Biopsy reveals malignant, spindle-shaped cells producing disorganized osteoid. Genetic testing of the tumor cells identifies a mutation in the TP53 gene. Which familial cancer syndrome is most commonly associated with this genetic profile?

. Multiple Endocrine Neoplasia type 1
. Li-Fraumeni syndrome
. Familial Adenomatous Polyposis
. Neurofibromatosis type 1
. McCune-Albright syndrome

Correct Answer & Explanation

. Li-Fraumeni syndrome

Explanation

Osteosarcoma is strongly associated with Li-Fraumeni syndrome, an autosomal dominant disorder caused by a germline mutation in the TP53 tumor suppressor gene. Patients are at high risk for sarcomas, breast cancer, brain tumors, and leukemia.

Question 6132

Topic: 10. Pathology and Oncology

A 35-year-old male presents with right hip pain. Radiographs reveal a benign-appearing, asymptomatic sessile osteochondroma of the proximal femur that has been stable for 15 years. The patient notes recent rapid growth and increasing pain. What MRI finding is most highly predictive of malignant transformation to a secondary chondrosarcoma?

. Cartilage cap thickness greater than 2 cm
. Intralesional hemorrhage and fluid-fluid levels
. Cortical disruption of the stalk
. Edema in the adjacent vastus lateralis
. Lack of continuity with the medullary canal

Correct Answer & Explanation

. Cartilage cap thickness greater than 2 cm

Explanation

In adults, a cartilage cap thickness of greater than 2 cm on MRI is highly suspicious for malignant transformation of an osteochondroma into a secondary chondrosarcoma. Rapid growth and new onset of pain also raise suspicion.

Question 6133

Topic: Bone Tumors

A 12-year-old girl presents with precocious puberty, cafe-au-lait spots with irregular 'coast of Maine' borders, and a radiolucent 'ground glass' lesion in her proximal femur causing a shepherd's crook deformity. What is the underlying pathophysiology of her bone disease?

. Failure of osteoclast resorption leading to dense bone
. Activating mutation of Gs-alpha (GNAS1 gene) leading to increased cAMP
. Vitamin D deficiency causing unmineralized osteoid
. Abnormal production of type 1 collagen causing brittle bones
. Defect in the parathyroid hormone receptor

Correct Answer & Explanation

. Activating mutation of Gs-alpha (GNAS1 gene) leading to increased cAMP

Explanation

This presentation is classic for McCune-Albright syndrome, consisting of polyostotic fibrous dysplasia, cafe-au-lait macules, and endocrine abnormalities. It is caused by a somatic activating mutation in the GNAS1 gene, resulting in elevated intracellular cAMP.

Question 6134

Topic: 10. Pathology and Oncology

A 68-year-old male presents with generalized bone pain, lethargy, and recurrent respiratory infections. Radiographs demonstrate multiple punched-out lytic lesions in the skull and axial skeleton.

What is the most appropriate initial screening laboratory test to establish the underlying diagnosis?

. Serum alkaline phosphatase
. Bone marrow biopsy with flow cytometry
. Serum and urine protein electrophoresis with immunofixation
. Technetium-99m whole-body bone scan
. Prostate-specific antigen (PSA)

Correct Answer & Explanation

. Serum and urine protein electrophoresis with immunofixation

Explanation

This patient's presentation and radiographic findings are classic for multiple myeloma. Serum and urine protein electrophoresis (SPEP/UPEP) with immunofixation are the most sensitive initial screening tests to detect monoclonal immunoglobulins. A skeletal survey is preferred over a Technetium-99m bone scan, which is often falsely negative due to the lack of reactive bone formation in myeloma.

Question 6135

Topic: 10. Pathology and Oncology

A 65-year-old man presents with intractable back pain. Radiographs reveal diffuse osteopenia and a vertebral compression fracture, while a skull radiograph shows punched-out lytic lesions.

What is the most definitive test to confirm the underlying diagnosis?

. Serum calcium level
. Urine immunofixation for Bence Jones protein
. Bone marrow biopsy
. Skeletal survey
. Serum protein electrophoresis (SPEP)

Correct Answer & Explanation

. Bone marrow biopsy

Explanation

While SPEP and urine immunofixation are standard screening tests, a bone marrow biopsy demonstrating greater than 10% clonal plasma cells is required for the definitive diagnosis of multiple myeloma. The presence of end-organ damage (CRAB criteria) further solidifies the clinical diagnosis.

Question 6136

Topic: 10. Pathology and Oncology

A 62-year-old patient with known multiple myeloma presents with a symptomatic lytic lesion in the proximal femur. The lesion involves 60% of the cortex, and the Mirels score is calculated to be 10. What is the most appropriate next step in management?

. Intravenous bisphosphonates and strict non-weight-bearing
. Radiation therapy alone
. Prophylactic internal fixation followed by postoperative radiation
. Systemic chemotherapy alone
. Core needle biopsy to confirm histology

Correct Answer & Explanation

. Prophylactic internal fixation followed by postoperative radiation

Explanation

A Mirels score of 9 or greater indicates a high risk for pathologic fracture (often >33%). Prophylactic surgical fixation is indicated, followed by radiation therapy to achieve local tumor control.

Question 6137

Topic: 10. Pathology and Oncology

A 16-year-old male is diagnosed with a conventional high-grade osteosarcoma of the distal femur. He undergoes 10 weeks of neoadjuvant chemotherapy followed by wide surgical resection. What is the most significant prognostic factor for long-term survival in this patient?

. Tumor size at initial presentation
. Specific histologic subtype (e.g., osteoblastic vs chondroblastic)
. Percentage of tumor necrosis found in the resection specimen
. Initial serum alkaline phosphatase level
. Presence of a periosteal Codman's triangle

Correct Answer & Explanation

. Percentage of tumor necrosis found in the resection specimen

Explanation

The degree of tumor necrosis after neoadjuvant chemotherapy (greater than or equal to 90% is considered a good response) is the most critical prognostic indicator for overall survival in conventional osteosarcoma.

Question 6138

Topic: 10. Pathology and Oncology

A 12-year-old boy presents with a permeative lytic lesion in the femoral diaphysis and an 'onion skin' periosteal reaction. Cytogenetics reveal a t(11;22) translocation. Which of the following fusion genes confirms the diagnosis?

. SYT-SSX
. EWS-FLI1
. FUS-CHOP
. PAX3-FKHR
. COL1A1-PDGFB

Correct Answer & Explanation

. EWS-FLI1

Explanation

The t(11;22) translocation is the hallmark of Ewing Sarcoma, resulting in the EWS-FLI1 fusion transcript. SYT-SSX is associated with Synovial Sarcoma, and FUS-CHOP with Myxoid Liposarcoma.

Question 6139

Topic: 10. Pathology and Oncology

A 55-year-old patient presents with localized bone pain and a single lytic lesion in the ilium without any other symptomatic sites.

What strict criteria must be met to diagnose a Solitary Bone Plasmacytoma rather than Multiple Myeloma?

. Normal skeletal survey/MRI, bone marrow biopsy showing <10% plasma cells, and absence of end-organ damage
. Elevated serum calcium and a single lytic bone lesion on CT
. Positive urine Bence Jones proteins with normal renal function
. Biopsy of the lesion showing giant cells and aneurysmal spaces
. Presence of anemia and a monoclonal M-spike >3g/dL

Correct Answer & Explanation

. Normal skeletal survey/MRI, bone marrow biopsy showing <10% plasma cells, and absence of end-organ damage

Explanation

Solitary bone plasmacytoma is diagnosed when there is a single biopsy-proven bone lesion of clonal plasma cells, with a normal skeletal survey/MRI, no end-organ damage (CRAB), and a bone marrow biopsy showing <10% plasma cells.

Question 6140

Topic: 10. Pathology and Oncology

A 55-year-old male presents with podagra. Joint fluid aspiration reveals negatively birefringent, needle-shaped crystals. For long-term chronic management, he is prescribed Allopurinol. What is its mechanism of action?

. Xanthine oxidase inhibitor
. Microtubule polymerization inhibitor
. Uricosuric agent blocking renal reabsorption
. Interleukin-1 (IL-1) receptor antagonist
. Tumor necrosis factor (TNF) alpha inhibitor

Correct Answer & Explanation

. Xanthine oxidase inhibitor

Explanation

Allopurinol is a xanthine oxidase inhibitor that decreases uric acid production, serving as the first-line urate-lowering therapy for chronic gout. Colchicine inhibits microtubules, and probenecid is a uricosuric agent.

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