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10. Pathology and Oncology MCQs

Practice Set 285 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 5681

Topic: 10. Pathology and Oncology
A 16-year-old male presents with distal femur pain. Imaging reveals a destructive lesion, and biopsy confirms a high-grade osteosarcoma. A staging MRI indicates that the tumor has breached the posterior cortex and extends into the surrounding vastus intermedius muscle, without evidence of skip lesions or distant metastasis. According to the Enneking Musculoskeletal Tumor Staging System, what is the stage of this lesion?
. Stage IA
. Stage IB
. Stage IIA
. Stage IIB
. Stage III

Correct Answer & Explanation

. Stage IIB

Explanation

The Enneking staging system evaluates histological grade (G), local extent/compartmentalization (T), and presence of metastasis (M). G1 = low grade, G2 = high grade. T1 = intracompartmental, T2 = extracompartmental. M0 = no metastasis, M1 = metastasis. This patient has a high-grade (G2) lesion that is extracompartmental (T2, extending through the cortex into the muscle) with no metastasis (M0). Therefore, it is Stage IIB. Any lesion with metastasis (M1) is classified as Stage III.

Question 5682

Topic: 10. Pathology and Oncology

A 25-year-old male presents with persistent night pain in his left tibia that is profoundly relieved by ibuprofen. Imaging shows a 1 cm radiolucent nidus surrounded by dense reactive sclerosis in the diaphyseal cortex. If the nidus is excised, histologic examination is most likely to show:

. Hyaline cartilage capping a bony stalk
. Fibroblastic stroma with a storiform pattern and scattered giant cells
. Interconnecting trabeculae of woven bone lined by prominent, plump osteoblasts
. Sheets of small round blue cells demonstrating positive CD99 staining
. Atypical spindle cells producing malignant, lace-like osteoid

Correct Answer & Explanation

. Interconnecting trabeculae of woven bone lined by prominent, plump osteoblasts

Explanation

The clinical presentation (night pain dramatically relieved by NSAIDs) and radiographic appearance (lucent nidus < 2 cm with dense reactive sclerosis) are pathognomonic for Osteoid Osteoma. Histologically, the nidus consists of a highly vascularized network of interconnecting woven bone trabeculae lined by prominent, plump osteoblasts without malignant stroma. Cartilage cap = osteochondroma. Storiform fibroblastic stroma = Non-ossifying fibroma. Small round blue cells = Ewing sarcoma. Malignant osteoid = Osteosarcoma.

Question 5683

Topic: 10. Pathology and Oncology

A 15-year-old boy presents with a 3-month history of a painful diaphyseal tibial lesion. The pain is worse at night and dramatically improves with NSAIDs. Radiographs show a small radiolucent nidus surrounded by reactive sclerosis. Which of the following inflammatory mediators is produced in high levels by this lesion?

. Interleukin-6 (IL-6)
. Tumor necrosis factor-alpha (TNF-a)
. Prostaglandin E2 (PGE2)
. Transforming growth factor-beta (TGF-b)
. Bone morphogenetic protein-2 (BMP-2)

Correct Answer & Explanation

. Prostaglandin E2 (PGE2)

Explanation

The clinical and radiographic presentation is classic for an osteoid osteoma. These benign bone-forming tumors possess a high expression of COX-2, leading to the production of extremely high levels of Prostaglandin E2 (PGE2). This pathophysiology explains the characteristic night pain that is exquisitely sensitive to NSAIDs.

Question 5684

Topic: 10. Pathology and Oncology

A 14-year-old girl is evaluated for a large, destructive mass in the diaphysis of her femur. Biopsy reveals sheets of small, round, blue cells. Cytogenetic analysis is most likely to reveal which of the following translocations?

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

Correct Answer & Explanation

. t(11;22)

Explanation

The clinical presentation and histology ('small round blue cells') are characteristic of Ewing sarcoma. The vast majority of Ewing sarcomas (>90%) are associated with the t(11;22)(q24;q12) chromosomal translocation, which results in the EWS-FLI1 fusion protein. t(9;22) is seen in CML; t(12;16) in myxoid liposarcoma; t(X;18) in synovial sarcoma; t(2;13) in alveolar rhabdomyosarcoma.

Question 5685

Topic: Bone Tumors

Which of the following is the most sensitive whole-body imaging modality for detecting skeletal marrow involvement in a patient newly diagnosed with multiple myeloma?

. Technetium-99m MDP bone scan
. Whole-body MRI
. Skeletal survey radiographs
. Dual-energy X-ray absorptiometry
. Gallium-67 scan

Correct Answer & Explanation

. Whole-body MRI

Explanation

Whole-body MRI is highly sensitive for detecting diffuse marrow infiltration and focal lesions in multiple myeloma long before cortical destruction becomes evident on plain radiographs. Standard bone scans (Tc-99m MDP) are notoriously 'cold' in myeloma because the lesions are purely lytic with little to no reactive bone formation.

Question 5686

Topic: 10. Pathology and Oncology

A 15-year-old male presents with a permeative, moth-eaten lytic lesion in the femoral diaphysis with an "onion-skin" periosteal reaction. Biopsy reveals small round blue cells. Which chromosomal translocation is highly specific for this pathology?

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

Correct Answer & Explanation

. t(11;22)

Explanation

The clinical presentation and histology are classic for Ewing sarcoma. The vast majority of these tumors contain the t(11;22)(q24;q12) translocation, which creates the oncogenic EWS-FLI1 fusion protein.

Question 5687

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with severe thigh pain. Radiographs show a destructive, permeative diaphyseal lesion of the femur with an 'onion-skin' periosteal reaction. Biopsy reveals small round blue cells. Which of the following chromosomal translocations is most pathognomonic for this tumor?

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

Correct Answer & Explanation

. t(11;22)

Explanation

This presentation is characteristic of Ewing sarcoma, a small round blue cell tumor. The t(11;22) translocation creates the EWS-FLI1 fusion protein, which is diagnostic for Ewing sarcoma.

Question 5688

Topic: Bone Tumors

A 19-year-old male presents with severe nocturnal thigh pain that is rapidly and completely relieved by ibuprofen. Radiographs demonstrate diaphyseal cortical thickening with a 1 cm radiolucent nidus. The dramatic pain relief is due to NSAID inhibition of which specific molecule secreted by the nidus?

. Interleukin-1 (IL-1)
. Prostaglandin E2 (PGE2)
. Tumor necrosis factor-alpha (TNF-a)
. Substance P
. Vascular endothelial growth factor (VEGF)

Correct Answer & Explanation

. Prostaglandin E2 (PGE2)

Explanation

This classic presentation describes an osteoid osteoma. The nidus secretes abnormally high levels of Prostaglandin E2 (PGE2), which mediates the severe nocturnal pain. NSAIDs provide dramatic relief by inhibiting cyclooxygenase, halting PGE2 synthesis.

Question 5689

Topic: 10. Pathology and Oncology

A 28-year-old male presents with a deep, painless mass in the popliteal fossa. Biopsy reveals a biphasic tumor with distinct epithelial and spindle cell components. Which of the following chromosomal translocations is characteristic of this neoplasm?

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

Correct Answer & Explanation

. t(X;18)

Explanation

The clinical and histologic description is classic for Synovial Sarcoma, which frequently presents in young adults near joints (though rarely within the joint space itself). It is characterized by the t(X;18) translocation, which fuses the SYT gene on chromosome 18 with SSX1 or SSX2 on the X chromosome. t(11;22) is Ewing sarcoma, t(9;22) is extraskeletal myxoid chondrosarcoma, t(12;16) is myxoid liposarcoma, and t(2;13) is alveolar rhabdomyosarcoma.

Question 5690

Topic: 10. Pathology and Oncology

A 19-year-old male presents with deep thigh pain that typically awakens him at night but is dramatically relieved by ibuprofen. Radiographs demonstrate a small intracortical radiolucent nidus surrounded by dense sclerosis. The profound pain relief provided by NSAIDs is primarily due to the high intralesional concentration of which of the following molecules?

. Interleukin-1
. Tumor necrosis factor-alpha
. Prostaglandin E2
. Substance P
. Bradykinin

Correct Answer & Explanation

. Prostaglandin E2

Explanation

The clinical picture is pathognomonic for an osteoid osteoma. These benign bone-forming tumors secrete unusually high levels of Prostaglandin E2 (PGE2), which mediates the severe nocturnal pain. Nonsteroidal anti-inflammatory drugs (NSAIDs) block the cyclooxygenase enzymes responsible for PGE2 synthesis, yielding the classic, rapid relief of symptoms.

Question 5691

Topic: 10. Pathology and Oncology

A 28-year-old female presents with progressive anterior knee pain. Radiographs reveal an eccentric, lytic epiphyseal lesion in the distal femur extending to the subchondral bone without a sclerotic border. Biopsy shows a background of mononuclear cells with numerous scattered multinucleated giant cells. Which of the following is the most appropriate initial surgical treatment?

. Observation with serial radiographs
. Radiofrequency ablation
. Intralesional extended curettage and filling with bone cement or graft
. Wide en bloc resection and endoprosthetic reconstruction
. Neoadjuvant radiation therapy followed by marginal excision

Correct Answer & Explanation

. Intralesional extended curettage and filling with bone cement or graft

Explanation

Giant cell tumors (GCT) of bone are benign but locally aggressive lesions that characteristically occur in the epiphyses of long bones in young adults. The standard of care is intralesional extended curettage (using a high-speed burr and chemical/thermal adjuvants) followed by filling the defect with polymethylmethacrylate (PMMA) or bone graft.

Question 5692

Topic: 10. Pathology and Oncology

A 16-year-old male is diagnosed with a localized high-grade intramedullary osteosarcoma of the distal femur. He undergoes 10 weeks of neoadjuvant chemotherapy followed by wide surgical resection. Which of the following is the most significant prognostic factor for his overall survival?

. Patient age at presentation
. Initial tumor volume on MRI
. Histologic percentage of tumor necrosis in the resected specimen
. Pre-treatment serum alkaline phosphatase level
. Surgical margins greater than 3 cm

Correct Answer & Explanation

. Histologic percentage of tumor necrosis in the resected specimen

Explanation

The histologic response to neoadjuvant chemotherapy (percentage of tumor necrosis in the resected specimen) is the single most important and reliable prognostic indicator for overall and disease-free survival in patients with osteosarcoma. >90% necrosis is considered a 'good response'.

Question 5693

Topic: 10. Pathology and Oncology

A 16-year-old boy presents with aching tibial pain that predictably worsens at night and is dramatically relieved by aspirin. Imaging reveals a 1 cm radiolucent nidus surrounded by dense sclerotic bone. What is the primary pathophysiological mechanism responsible for the profound pain associated with this lesion?

. High concentrations of local tumor necrosis factor-alpha irritating the periosteum
. Mechanical compression of the periosteal nerve endings by reactive sclerosis
. High levels of prostaglandin E2 sensitizing unmyelinated nerve fibers within the nidus
. Direct tumor invasion into adjacent intra-osseous neurovascular bundles
. Histamine release from infiltrating mast cells triggering a local inflammatory cascade

Correct Answer & Explanation

. High levels of prostaglandin E2 sensitizing unmyelinated nerve fibers within the nidus

Explanation

Osteoid osteomas are characterized by a radiolucent nidus (<1.5 cm) surrounded by reactive sclerosis. They produce up to 1000 times the normal level of prostaglandin E2 (PGE2) and cyclooxygenase-2 (COX-2). PGE2 sensitizes the dense network of local unmyelinated nerve fibers present within the nidus, causing severe night pain. The pain is characteristically relieved by NSAIDs or aspirin, which inhibit COX and decrease PGE2 production.

Question 5694

Topic: 10. Pathology and Oncology

A 12-year-old boy presents with a permeative lytic lesion in the diaphysis of his femur with an associated 'onion-skin' periosteal reaction. Biopsy reveals sheets of uniform, small round blue cells that are CD99 positive. Which of the following chromosomal translocations is most characteristic of this neoplasm?

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

Correct Answer & Explanation

. t(11;22)(q24;q12)

Explanation

The clinical scenario describes Ewing sarcoma, characterized by a permeative diaphyseal lesion, 'onion-skin' periostitis, and small round blue cells expressing CD99 (MIC2). The classic molecular hallmark is the t(11;22)(q24;q12) translocation, which results in the EWS-FLI1 fusion protein. t(12;16) is seen in myxoid liposarcoma. t(2;13) is seen in alveolar rhabdomyosarcoma. t(X;18) is characteristic of synovial sarcoma.

Question 5695

Topic: Bone Tumors

A 22-year-old male presents with dull, aching pain in his posterior mid-thoracic spine that is poorly relieved by NSAIDs. CT imaging reveals a 3.0 cm expansile, radiolucent lesion in the right T8 lamina with a thin sclerotic margin and focal internal mineralization. Histologic examination shows interlacing trabeculae of woven bone lined by a single layer of plump, uniform osteoblasts. What is the most likely diagnosis?

. Osteoid osteoma
. Aneurysmal bone cyst
. Osteoblastoma
. Chondroblastoma
. Osteosarcoma

Correct Answer & Explanation

. Osteoblastoma

Explanation

The clinical, radiographic, and histologic presentation is classic for an osteoblastoma. Histologically, osteoblastoma is identical to osteoid osteoma (woven bone trabeculae lined by plump osteoblasts with a vascular stroma). However, osteoblastoma is differentiated clinically and radiographically by its larger size (typically > 2.0 cm), predilection for the posterior elements of the spine, and a pain pattern that is less reliably relieved by NSAIDs compared to the classic night pain of osteoid osteoma.

Question 5696

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with a permeative lytic lesion in the diaphysis of his femur with an associated "onion-skin" periosteal reaction. Histology reveals small, round blue cells positive for CD99. Which translocation is most likely present?

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

Correct Answer & Explanation

. t(11;22)

Explanation

The patient has Ewing sarcoma, which is classically associated with the t(11;22) chromosomal translocation resulting in the EWS-FLI1 fusion protein. It typically presents in the diaphysis of long bones in children.

Question 5697

Topic: Bone Tumors

A 19-year-old male complains of severe left thigh pain that is worse at night and dramatically relieved by ibuprofen. Radiographs show a small radiolucent nidus surrounded by dense sclerotic bone in the proximal femur. Which of the following enzymes is typically found in high concentrations within the nidus?

. Lipoxygenase
. Cyclooxygenase-2 (COX-2)
. Acid phosphatase
. Matrix metalloproteinase-9
. Alkaline phosphatase

Correct Answer & Explanation

. Cyclooxygenase-2 (COX-2)

Explanation

The classic presentation of an osteoid osteoma includes nocturnal pain relieved by NSAIDs. This characteristic pain is driven by the high levels of prostaglandins produced by increased COX-2 expression within the nidus.

Question 5698

Topic: 10. Pathology and Oncology

A 15-year-old female presents with progressive knee pain and swelling. Radiographs reveal a sunburst periosteal reaction and Codman's triangle in the distal femur. Biopsy confirms high-grade osteosarcoma. Which of the following factors is considered the single most important prognostic indicator for her long-term survival?

. Tumor size at presentation
. Histologic subtype of the tumor
. Percentage of tumor necrosis following neoadjuvant chemotherapy
. Presence of a skip metastasis on MRI
. Alkaline phosphatase level at diagnosis

Correct Answer & Explanation

. Percentage of tumor necrosis following neoadjuvant chemotherapy

Explanation

In high-grade osteosarcoma, the histologic response to neoadjuvant chemotherapy (percentage of tumor necrosis) is the single most important prognostic factor. A response of 90% or greater necrosis indicates a favorable prognosis.

Question 5699

Topic: 10. Pathology and Oncology

A 12-year-old boy presents with a permeative diaphyseal lesion in his femur with an associated "onion-skin" periosteal reaction. Which of the following chromosomal translocations is most strongly associated with this diagnosis?

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

Correct Answer & Explanation

. t(11;22)

Explanation

The clinical and radiographic presentation is classic for Ewing sarcoma. This aggressive bone tumor is strongly associated with the t(11;22) chromosomal translocation, which results in the EWS-FLI1 fusion protein.

Question 5700

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with a destructive diaphyseal lesion of the femur with an associated soft tissue mass. Biopsy reveals small round blue cells. Which of the following molecular abnormalities is most classically associated with this patient's likely diagnosis?

. t(11;22)(q24;q12) translocation involving EWSR1 and FLI1
. t(X;18)(p11;q11) translocation involving SYT and SSX
. t(12;16)(q13;p11) translocation involving FUS and DDIT3
. Amplification of MDM2 and CDK4 genes
. Mutations in the EXT1 or EXT2 genes

Correct Answer & Explanation

. t(11;22)(q24;q12) translocation involving EWSR1 and FLI1

Explanation

The patient's clinical and histologic picture (diaphyseal lesion, small round blue cells) is classic for Ewing sarcoma. Ewing sarcoma is heavily characterized by the t(11;22)(q24;q12) chromosomal translocation, which results in the EWSR1-FLI1 fusion protein (found in roughly 85% of cases). t(X;18) is associated with Synovial sarcoma. t(12;16) is associated with Myxoid liposarcoma. MDM2 amplification is characteristic of well-differentiated liposarcoma/parosteal osteosarcoma.

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