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10. Pathology and Oncology MCQs

Practice Set 156 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 3101

Topic: 10. Pathology and Oncology
A 55-year-old man presents with progressive pain in his proximal humerus. Radiographs show a lytic lesion with intralesional "popcorn" calcifications and endosteal scalloping involving >2/3 of the cortical thickness. Biopsy confirms a grade 2 chondrosarcoma. What is the optimal initial treatment?
. Intralesional curettage and bone grafting
. Wide surgical resection
. Definitive radiation therapy
. Systemic multidrug chemotherapy
. Radiofrequency ablation

Correct Answer & Explanation

. Wide surgical resection

Explanation

Conventional intermediate to high-grade chondrosarcomas are notably resistant to both conventional chemotherapy and radiation. Wide surgical resection with negative margins remains the mainstay of curative treatment.

Question 3102

Topic: Bone Tumors

A 12-year-old girl presents with pain and swelling of her distal femur. MRI reveals an expansile, multiloculated metaphyseal lesion containing multiple fluid-fluid levels. Genetic testing of the biopsy specimen identifies a rearrangement of the USP6 gene. What is the diagnosis?

. Unicameral bone cyst
. Giant cell tumor of bone
. Telangiectatic osteosarcoma
. Aneurysmal bone cyst
. Fibrous dysplasia

Correct Answer & Explanation

. Aneurysmal bone cyst

Explanation

Primary aneurysmal bone cysts (ABCs) are characterized radiographically by fluid-fluid levels on MRI and genetically by translocations involving the USP6 gene on chromosome 17p13.

Question 3103

Topic: 10. Pathology and Oncology

A 19-year-old male complains of severe, unrelenting night pain in his proximal tibia, which is completely relieved within 30 minutes of taking ibuprofen. A high-resolution CT scan shows a 7 mm radiolucent nidus surrounded by intense reactive sclerosis. What is the pathophysiologic mechanism directly responsible for the pain?

. Compression of adjacent nerve rootlets
. High local production of prostaglandins (PGE2)
. Microfractures within the dense sclerotic bone
. Rapid tumor expansion causing periosteal stretching
. Ischemia secondary to tumor micro-emboli

Correct Answer & Explanation

. High local production of prostaglandins (PGE2)

Explanation

Osteoid osteomas produce exceptionally high levels of prostaglandins, specifically PGE2, which dramatically lowers the pain threshold. This mechanism explains the classic, dramatic relief of pain with NSAIDs.

Question 3104

Topic: 10. Pathology and Oncology

A 25-year-old man presents with a slow-growing, painful mass in the anterior mid-diaphysis of his tibia. Radiographs reveal a multilocular, eccentric "soap-bubble" lytic lesion. Histological analysis demonstrates a biphasic pattern consisting of an epithelial component embedded within a bland osteofibrous stroma. What is the diagnosis?

. Fibrous dysplasia
. Osteofibrous dysplasia
. Adamantinoma
. Langerhans cell histiocytosis
. Enchondroma

Correct Answer & Explanation

. Adamantinoma

Explanation

Adamantinoma is a rare, low-grade malignant bone tumor that almost exclusively occurs in the tibial diaphysis. It is uniquely characterized by its biphasic histology, containing both epithelial (keratin-positive) and osteofibrous components.

Question 3105

Topic: Bone Tumors
A 9-year-old girl is evaluated for precocious puberty, hyperpigmented cutaneous macules with irregular borders, and multiple expansile bone lesions exhibiting a "ground-glass" matrix on radiographs. This syndrome is caused by a somatic activating mutation in which of the following genes?
. GNAS
. EXT1
. NF1
. PTEN
. SH3BP2

Correct Answer & Explanation

. GNAS

Explanation

The patient has McCune-Albright syndrome, characterized by polyostotic fibrous dysplasia, precocious puberty, and "coast of Maine" café-au-lait spots. It is caused by a somatic, post-zygotic activating mutation in the GNAS gene.

Question 3106

Topic: 10. Pathology and Oncology

A 60-year-old woman presents with a purely destructive lytic lesion in her proximal humerus. An image-guided biopsy shows clear cell morphology consistent with a metastatic carcinoma. Prior to proceeding with prophylactic internal fixation, what critical preoperative study must be obtained to prevent a catastrophic intraoperative complication?

. Technetium-99m bone scan
. Complete skeletal survey
. Angiography and possible embolization
. Serum protein electrophoresis
. Dual-energy X-ray absorptiometry (DEXA) scan

Correct Answer & Explanation

. Angiography and possible embolization

Explanation

The scenario describes metastatic renal cell carcinoma (lytic lesion, clear cells). Renal and thyroid metastases are highly vascular; therefore, preoperative angiography and embolization are crucial to prevent massive intraoperative hemorrhage.

Question 3107

Topic: 10. Pathology and Oncology

A 55-year-old man presents with progressive bowel and bladder dysfunction. MRI reveals a large, destructive, midline sacral mass. Biopsy reveals cords of cells with bubbly, vacuolated cytoplasm that immunostain positive for brachyury. What is the embryological origin of this tumor?

. Neural crest cells
. Notochord
. Paraxial mesoderm
. Endoderm
. Surface ectoderm

Correct Answer & Explanation

. Notochord

Explanation

Chordomas are locally aggressive, low-grade malignant tumors that arise from the remnants of the embryonic notochord. They are uniquely defined histologically by physaliferous (bubbly) cells and immunohistochemically by brachyury expression.

Question 3108

Topic: Bone Tumors

An 8-year-old boy sustains a low-energy fracture of the proximal humerus. Radiographs show a centrally located, completely radiolucent metaphyseal lesion with a piece of cortical bone resting dependently at the bottom of the cyst cavity. What is this pathognomonic radiographic sign called?

. Shepherd's crook sign
. Fallen leaf sign
. Sunburst pattern
. Onion-skinning
. Popcorn calcification

Correct Answer & Explanation

. Fallen leaf sign

Explanation

The "fallen leaf" or "fallen fragment" sign occurs when a piece of fractured cortex falls through the fluid-filled cavity to the dependent portion of the lesion. It is highly specific for a unicameral (simple) bone cyst.

Question 3109

Topic: 10. Pathology and Oncology

A 12-year-old girl is diagnosed with multiple enchondromatosis. Physical examination also reveals numerous soft tissue hemangiomas with visible phleboliths on extremity radiographs. Which syndrome does she have, and what is her lifetime risk of malignant transformation to chondrosarcoma?

. Ollier disease, 10-20%
. Maffucci syndrome, up to 100%
. Multiple hereditary exostoses, 5%
. McCune-Albright syndrome, 1%
. Trevor disease, 50%

Correct Answer & Explanation

. Maffucci syndrome, up to 100%

Explanation

Maffucci syndrome is distinguished from Ollier disease by the concomitant presence of soft tissue hemangiomas. It carries an extremely high lifetime risk of malignant transformation to chondrosarcoma, approaching 100%.

Question 3110

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with a painful diaphyseal mass in the femur. Biopsy reveals uniform small round blue cells. Cytogenetic analysis identifies a t(11;22)(q24;q12) translocation. Which of the following fusion proteins is driving this pathology?

. SYT-SSX1
. EWS-FLI1
. TLS-CHOP
. PAX3-FKHR
. COL1A1-PDGFB

Correct Answer & Explanation

. EWS-FLI1

Explanation

Ewing sarcoma classically presents as a diaphyseal bone lesion in adolescents, histologically appearing as small round blue cells. The characteristic t(11;22) translocation results in the EWS-FLI1 fusion protein.

Question 3111

Topic: 10. Pathology and Oncology
A 65-year-old man presents with a painful proximal humerus mass. Radiographs show a destructive medullary lesion with intralesional "popcorn" calcifications and endosteal scalloping involving >2/3 of the cortical thickness. What is the most appropriate definitive management?
. Intralesional curettage and bone grafting
. Wide surgical resection
. Neoadjuvant chemotherapy followed by resection
. Primary fractionated radiation therapy
. Targeted Denosumab therapy

Correct Answer & Explanation

. Wide surgical resection

Explanation

This clinical and radiographic picture strongly suggests conventional chondrosarcoma. Wide surgical resection is the mainstay of treatment, as these tumors are generally resistant to both traditional chemotherapy and radiation.

Question 3112

Topic: Bone Tumors

A 16-year-old boy presents with severe nocturnal thigh pain that is completely relieved by ibuprofen. Imaging shows a 1 cm radiolucent nidus surrounded by dense reactive sclerosis in the femoral diaphysis. What is the primary mechanism of pain relief by NSAIDs in this condition?

. Inhibition of COX-2 mediated prostaglandin E2 (PGE2) production by the nidus
. Direct reduction of intraosseous pressure within the medullary canal
. Suppression of osteoclastic bone resorption at the sclerotic rim
. Inhibition of substance P release in the surrounding periosteum
. Vasoconstriction of feeding vessels to the nidus

Correct Answer & Explanation

. Inhibition of COX-2 mediated prostaglandin E2 (PGE2) production by the nidus

Explanation

Osteoid osteomas characteristically produce high levels of prostaglandin E2 (PGE2) due to intense COX-2 expression within the nidus. NSAIDs relieve pain by directly inhibiting this COX-mediated PGE2 production.

Question 3113

Topic: Bone Tumors

A 25-year-old patient presents with a "shepherd's crook" deformity of the proximal femur. Radiographs show an expansile lesion with a "ground-glass" appearance. A somatic activating mutation in which of the following genes is characteristic of this condition?

. GNAS
. EXT1
. RB1
. TP53
. FGFR3

Correct Answer & Explanation

. GNAS

Explanation

Fibrous dysplasia is caused by a post-zygotic, somatic activating mutation in the GNAS gene. This leads to increased intracellular cAMP, which impairs the normal differentiation of bone-forming cells.

Question 3114

Topic: 10. Pathology and Oncology

A 15-year-old girl presents with a rapidly expansile, eccentric lytic lesion in the distal femur. MRI reveals multiple fluid-fluid levels. Genetic analysis of the biopsy reveals a USP6 gene rearrangement. What is the optimal surgical treatment?

. Extended curettage with high-speed burring and bone grafting/cementing
. Wide en bloc resection with endoprosthetic reconstruction
. Above-knee amputation
. Neoadjuvant chemotherapy followed by marginal excision
. Observation as the lesion will spontaneously regress

Correct Answer & Explanation

. Extended curettage with high-speed burring and bone grafting/cementing

Explanation

Aneurysmal bone cysts (ABCs) carrying USP6 translocations are considered primary neoplastic lesions rather than purely reactive ones. Extended intralesional curettage using a high-speed burr, followed by local adjuvants and grafting/cementing, is the standard of care with low recurrence rates.

Question 3115

Topic: 10. Pathology and Oncology

A 30-year-old man presents with a slow-growing, painful mass near the knee joint, distinct from the joint space. Imaging shows stippled calcifications within the soft tissue mass. Biopsy reveals a biphasic spindle cell pattern. Which chromosomal translocation is diagnostic for this tumor?

. t(X;18)(p11;q11)
. t(11;22)(q24;q12)
. t(12;16)(q13;p11)
. t(2;13)(q35;q14)
. t(9;22)(q34;q11)

Correct Answer & Explanation

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

Explanation

Synovial sarcoma frequently occurs near large joints (but rarely inside the joint space) and is classically characterized by the t(X;18)(p11;q11) translocation. This chromosomal abnormality results in the SYT-SSX fusion gene.

Question 3116

Topic: 10. Pathology and Oncology

A 12-year-old boy undergoes a knee radiograph after an ankle sprain. An incidental eccentrically located, multi-loculated, radiolucent lesion with a sclerotic rim is seen in the distal femoral metaphysis, occupying less than 25% of the bone diameter. What is the most appropriate management?

. Intralesional curettage and bone grafting
. Core needle biopsy to rule out malignancy
. Observation and reassurance
. Wide local excision
. Prophylactic internal fixation

Correct Answer & Explanation

. Observation and reassurance

Explanation

This classic presentation describes a non-ossifying fibroma (NOF), a common, benign, self-limiting fibro-osseous defect of childhood. Asymptomatic lesions that do not compromise structural integrity require only observation and reassurance, as they typically ossify by early adulthood.

Question 3117

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with a destructive metadiaphyseal lesion in the distal femur. Biopsy confirms high-grade osteosarcoma. Which of the following tumor suppressor genes are most commonly implicated in the pathogenesis of this tumor?

. BRCA1 and BRCA2
. TP53 and RB1
. APC and MLH1
. EXT1 and EXT2
. NF1 and NF2

Correct Answer & Explanation

. TP53 and RB1

Explanation

Osteosarcoma is frequently associated with mutations in the TP53 (Li-Fraumeni syndrome) and RB1 (Retinoblastoma) tumor suppressor genes. These mutations lead to uncontrolled cell cycle progression and malignant transformation.

Question 3118

Topic: 10. Pathology and Oncology

A 10-year-old boy presents with a painful, swollen thigh and low-grade fever. Radiographs show a permeative diaphyseal lesion with an "onion-skin" periosteal reaction. Biopsy reveals small, round blue cells. Which chromosomal translocation is highly diagnostic?

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

Correct Answer & Explanation

. t(11;22)

Explanation

Ewing sarcoma is characterized by the t(11;22)(q24;q12) translocation, resulting in the EWSR1-FLI1 fusion protein. It typically presents as a permeative diaphyseal lesion in children.

Question 3119

Topic: 10. Pathology and Oncology

A 15-year-old boy undergoes neoadjuvant chemotherapy followed by limb-salvage surgery for a high-grade, intramedullary osteosarcoma of the distal femur. What is the most important prognostic factor for his long-term survival?

. Tumor size at the time of initial presentation
. The anatomic location of the primary tumor
. Percentage of tumor necrosis following neoadjuvant chemotherapy
. The presence of a Codman's triangle on preoperative radiographs
. The specific chemotherapeutic agents used postoperatively

Correct Answer & Explanation

. Percentage of tumor necrosis following neoadjuvant chemotherapy

Explanation

The most important prognostic factor for long-term survival in patients with high-grade osteosarcoma without metastases at presentation is the histological response to neoadjuvant chemotherapy. A favorable response is defined as greater than 90% tumor necrosis upon pathologic evaluation of the resected specimen.

Question 3120

Topic: 10. Pathology and Oncology

A 12-year-old girl presents with fever, elevated ESR, and a permeative diaphyseal lesion in her femur with 'onion skin' periosteal reaction. A biopsy is performed. Which chromosomal translocation is classically associated with her diagnosis?

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

Correct Answer & Explanation

. t(11;22)

Explanation

The patient's presentation and imaging are classic for Ewing sarcoma. This tumor is strongly associated with the t(11;22) translocation, which creates the EWS-FLI1 fusion protein that acts as an aberrant transcription factor driving oncogenesis.

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