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10. Pathology and Oncology MCQs

Practice Set 141 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 2801

Topic: 10. Pathology and Oncology

A 19-year-old male complains of a dull, aching pain in his right shin that is consistently worse at night and dramatically relieved by taking ibuprofen. Radiographs reveal a thickened cortical diaphysis with a 7-mm radiolucent nidus. The intense pain experienced by this patient is primarily mediated by local overproduction of which of the following substances?

. Interleukin-1 (IL-1)
. Substance P
. Prostaglandin E2 (PGE2)
. Tumor necrosis factor-alpha (TNF-alpha)
. Bradykinin

Correct Answer & Explanation

. Prostaglandin E2 (PGE2)

Explanation

Osteoid osteomas are benign, bone-forming tumors characterized by a small radiolucent nidus surrounded by dense, reactive sclerotic bone. Patients classically present with nocturnal pain that is characteristically relieved by NSAIDs or aspirin. This intense pain is mediated by very high levels of prostaglandins, specifically Prostaglandin E2 (PGE2), which is produced in large quantities by the neoplastic osteoblasts within the nidus. NSAIDs act by inhibiting cyclooxygenase (COX), thereby decreasing prostaglandin synthesis and providing dramatic symptomatic relief.

Question 2802

Topic: 10. Pathology and Oncology

A 35-year-old woman undergoes arthroscopic synovectomy for a diffuse, recurrent, and hemorrhagic joint effusion in her left knee. Histopathology shows a hyperplastic synovium with a proliferation of mononuclear cells, multinucleated giant cells, and abundant hemosiderin deposition. The primary molecular driver of this condition is a genetic alteration resulting in the overexpression of which of the following?

. Colony-Stimulating Factor 1 (CSF1)
. Guanine nucleotide-binding protein alpha-stimulating activity polypeptide 1 (GNAS)
. Murine double minute 2 (MDM2)
. Fibroblast growth factor receptor 3 (FGFR3)
. Cadherin-11 (CDH11)

Correct Answer & Explanation

. Colony-Stimulating Factor 1 (CSF1)

Explanation

The patient's presentation and histologic findings are classic for Pigmented Villonodular Synovitis (PVNS), currently classified by the WHO as diffuse Tenosynovial Giant Cell Tumor (TGCT). The pathogenesis of TGCT is driven by a chromosomal translocation, typically t(1;2)(p13;q37), which links the COL6A3 promoter to the CSF1 gene. This results in the overexpression of Colony-Stimulating Factor 1 (CSF1) by a small clone of neoplastic cells. This creates a 'landscaping effect' that recruits a large secondary population of non-neoplastic inflammatory cells (macrophages and multinucleated giant cells) that express the CSF1 receptor. This mechanism is the target for therapies like pexidartinib.

Question 2803

Topic: 10. Pathology and Oncology
A 55-year-old man is found to have a 6-cm painful lesion in his proximal humerus. Radiographs show a radiolucent lesion with endosteal scalloping greater than two-thirds of the cortical thickness and distinct areas of 'popcorn' calcification. Biopsy reveals hypercellular hyaline cartilage with binucleated cells and a myxoid stroma. Which of the following is the most appropriate definitive management for this lesion?
. Intralesional curettage, high-speed burring, and bone grafting
. Systemic chemotherapy followed by intralesional curettage
. Primary stereotactic radiation therapy
. Wide en bloc surgical resection
. Observation with serial radiographs every 6 months

Correct Answer & Explanation

. Wide en bloc surgical resection

Explanation

The lesion has aggressive radiographic features (deep endosteal scalloping, pain, larger size) and histology (hypercellularity, binucleated cells, myxoid stroma) consistent with a higher-grade (Grade II or III) conventional chondrosarcoma. Conventional chondrosarcomas are notoriously resistant to both chemotherapy and radiation therapy due to their poor vascularity, slow growth, and dense extracellular matrix. The gold standard and mainstay of treatment for conventional chondrosarcoma (Grade II or higher) is wide surgical resection. Intralesional curettage is only acceptable for highly selected, inactive Grade I atypical cartilaginous tumors in the appendicular skeleton.

Question 2804

Topic: 10. Pathology and Oncology

A 4-year-old boy presents with a rapidly growing mass in his proximal forearm. An incisional biopsy confirms the diagnosis of rhabdomyosarcoma. Which of the following statements is true regarding the typical staging and biological behavior of this patient's disease?

. Alveolar rhabdomyosarcoma is the most common histologic subtype in this age group
. The embryonal subtype is classically associated with the t(2;13) translocation
. Unlike most soft tissue sarcomas, it has a high propensity for lymphatic metastasis
. Surgical resection alone with negative margins is the standard of care for localized disease
. Positive immunohistochemical staining for S-100 is required for definitive diagnosis

Correct Answer & Explanation

. Unlike most soft tissue sarcomas, it has a high propensity for lymphatic metastasis

Explanation

Rhabdomyosarcoma is the most common soft tissue sarcoma in childhood. It is clinically distinct from most adult sarcomas because it has a high propensity for lymphatic spread (10-20%), warranting careful regional lymph node evaluation. Embryonal is the most common subtype overall, particularly in younger children. The alveolar subtype, which carries a worse prognosis, is associated with the t(2;13) or t(1;13) translocations involving the PAX3/PAX7 and FOXO1 genes. Treatment is always multimodal, requiring systemic chemotherapy in addition to local control (surgery and/or radiation). Diagnosis relies on muscle-specific markers such as desmin, myogenin, and MyoD1, not S-100.

Question 2805

Topic: Bone Tumors
A 22-year-old woman sustains a pathologic fracture of her proximal femur. Pre-injury radiographs obtained from an outside hospital reveal a 'ground-glass' appearance of the medullary canal with a severe varus 'shepherd's crook' deformity. Physical examination notes large, irregular café-au-lait macules on her trunk. An activating somatic mutation in which of the following genes is fundamentally responsible for her condition?
. GNAS
. EXT1
. FGFR3
. PTH1R
. RET

Correct Answer & Explanation

. GNAS

Explanation

The patient presents with polyostotic fibrous dysplasia and café-au-lait macules (with irregular 'coast of Maine' borders), indicating McCune-Albright syndrome. Fibrous dysplasia is caused by a somatic, post-zygotic activating missense mutation in the GNAS gene. This gene encodes the alpha subunit of the stimulatory G protein (Gs-alpha). The mutation leads to constitutively increased intracellular cyclic AMP (cAMP), which disrupts the normal differentiation of osteoblasts, resulting in the characteristic proliferation of immature spindle cells and poorly formed woven bone (the 'ground-glass' appearance on radiographs).

Question 2806

Topic: 10. Pathology and Oncology

A 34-year-old man presents with chronic, progressive aching pain in his anterior left shin. Radiographs demonstrate a multiloculated, eccentric, lytic lesion in the anterior cortex of the tibial diaphysis. Biopsy reveals a biphasic pattern with clusters of epithelial cells surrounded by a dense, spindle-cell osteofibrous stroma. What is the most appropriate management for this lesion?

. Intralesional curettage with adjuvant phenol and bone grafting
. Wide en bloc resection and reconstruction
. Primary below-knee amputation
. Neoadjuvant radiation therapy followed by curettage
. Observation with protected weight-bearing

Correct Answer & Explanation

. Wide en bloc resection and reconstruction

Explanation

The clinical location (anterior tibial cortex) and biphasic histologic presentation (epithelial nests within an osteofibrous stroma) are virtually pathognomonic for adamantinoma. Adamantinoma is a rare, low-grade, malignant bone tumor. Because it is locally aggressive and carries the potential for both local recurrence and distant metastasis (most commonly to the lungs or regional lymph nodes), the treatment of choice is wide en bloc resection with margin-negative reconstruction. It is largely resistant to chemotherapy and radiation. Amputation is strictly reserved for cases where wide resection and limb salvage are anatomically impossible.

Question 2807

Topic: Bone Tumors

A 19-year-old man presents with right thigh pain that is worse at night and dramatically relieved by ibuprofen. CT scan shows a 9-mm radiolucent nidus surrounded by dense reactive bone in the lesser trochanter. If the patient is intolerant to long-term NSAID use, what is the most appropriate next step in management?

. Wide resection
. Marginal excision
. Percutaneous radiofrequency ablation
. Intralesional steroid injection
. External beam radiation therapy

Correct Answer & Explanation

. Percutaneous radiofrequency ablation

Explanation

The clinical presentation and radiographic findings are classic for an osteoid osteoma. While observation with NSAIDs is the first-line treatment for many patients, percutaneous radiofrequency ablation (RFA) is the gold standard surgical/interventional treatment in the appendicular skeleton when medical management fails or is not tolerated. It offers a highly successful, minimally invasive alternative to surgical resection.

Question 2808

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with progressive, activity-related right knee pain. Radiographs demonstrate a well-defined, 2-cm eccentrically located lytic lesion in the proximal tibial epiphysis with a thin sclerotic rim. A biopsy reveals polygonal chondroblasts, multinucleated giant cells, and 'chicken-wire' calcification. What is the most appropriate definitive management?

. Intralesional curettage and bone grafting
. Wide resection and endoprosthetic reconstruction
. Chemotherapy followed by surgical resection
. Denosumab therapy
. Radiation therapy

Correct Answer & Explanation

. Intralesional curettage and bone grafting

Explanation

The clinical, radiographic, and histologic presentations are classic for chondroblastoma, a benign but locally aggressive primary bone tumor that classically arises in the epiphysis of skeletally immature patients. The pathognomonic histologic feature is fine, pericellular 'chicken-wire' calcification. The standard of care is extended intralesional curettage (with a high-speed burr) and filling the defect with bone graft or bone cement.

Question 2809

Topic: 10. Pathology and Oncology

A 9-year-old boy presents with progressive diaphyseal pain and a palpable mass in his left femur. Radiographs show an ill-defined permeative lytic lesion with an 'onion-skin' periosteal reaction. A core needle biopsy confirms Ewing sarcoma. Which of the following cytogenetic abnormalities is most characteristically associated with this tumor?

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

Correct Answer & Explanation

. t(11;22)

Explanation

Ewing sarcoma is classically associated with the t(11;22)(q24;q12) translocation, resulting in the EWS-FLI1 fusion protein in approximately 85% of cases. The t(X;18) translocation is associated with synovial sarcoma; t(9;22) is seen in extraskeletal myxoid chondrosarcoma (and CML); t(2;13) is associated with alveolar rhabdomyosarcoma; and t(12;16) is seen in myxoid liposarcoma.

Question 2810

Topic: 10. Pathology and Oncology

A 45-year-old woman undergoes a shoulder radiograph after a minor mechanical fall. The film reveals an incidental 3-cm lobulated radiolucent lesion in the proximal humeral metaphysis with internal stippled and 'rings-and-arcs' calcifications. There is no endosteal scalloping, cortical breakthrough, periosteal reaction, or associated soft tissue mass. What is the most appropriate management?

. Core needle biopsy
. Wide surgical resection
. Intralesional curettage and bone grafting
. Observation with serial radiographs
. Positron emission tomography (PET) scan

Correct Answer & Explanation

. Observation with serial radiographs

Explanation

The presentation describes an incidental enchondroma, a benign cartilaginous tumor. Features such as 'rings-and-arcs' calcifications without aggressive characteristics (no deep endosteal scalloping, cortical destruction, or periosteal reaction) and the lack of tumor-related pain heavily support a benign process. Observation with serial clinical and radiographic follow-up is the standard of care.

Question 2811

Topic: 10. Pathology and Oncology
A 65-year-old man presents with severe lower back pain and fatigue. Laboratory studies show hypercalcemia, anemia, and an elevated serum creatinine. A skeletal survey reveals multiple punched-out lytic lesions in the skull and vertebral bodies. Bone marrow biopsy reveals >10% clonal plasma cells. Which of the following radiographic features best distinguishes this disease from osteolytic bone metastases?
. Frequent involvement of the mandible
. Involvement of the pedicles early in the disease process
. Bone scintigraphy demonstrating intense radiotracer uptake
. Lesions characteristically showing surrounding reactive sclerosis
. Relative sparing of the posterior elements of the spine

Correct Answer & Explanation

. Relative sparing of the posterior elements of the spine

Explanation

Multiple myeloma classically demonstrates 'punched-out' lytic lesions without reactive sclerosis. In the spine, it frequently involves the vertebral bodies while relatively sparing the posterior elements (e.g., pedicles) until late in the disease. In contrast, osteolytic metastases often involve the pedicles early (the 'winking owl' sign). Additionally, bone scans are typically 'cold' or negative in multiple myeloma due to osteoblast suppression, whereas they are usually positive in metastatic bone disease.

Question 2812

Topic: 10. Pathology and Oncology

A 15-year-old girl is diagnosed with high-grade conventional intramedullary osteosarcoma of the distal femur. She completes a standard regimen of neoadjuvant chemotherapy and undergoes a limb-salvage surgical resection. Assuming she has no distant metastases at presentation, which of the following is the most important prognostic factor for her overall survival?

. Percentage of tumor necrosis on the resected specimen
. Initial tumor volume
. Patient age at presentation
. Specific histologic subtype of the osteosarcoma
. Serum alkaline phosphatase level at presentation

Correct Answer & Explanation

. Percentage of tumor necrosis on the resected specimen

Explanation

In localized high-grade osteosarcoma, the histologic response to neoadjuvant chemotherapy, determined by the percentage of tumor necrosis in the definitive resection specimen, is the most powerful predictor of disease-free and overall survival. A good response is typically defined as greater than or equal to 90% necrosis (Huvos grading system).

Question 2813

Topic: Bone Tumors

A 7-year-old boy presents with mild right arm pain after throwing a baseball. Radiographs show a centrally located, well-circumscribed radiolucent lesion in the proximal humeral metaphysis spanning the width of the medullary canal. A small fragment of bone is seen resting in the dependent portion of the cystic lesion. What is the most likely diagnosis?

. Aneurysmal bone cyst
. Eosinophilic granuloma
. Unicameral bone cyst
. Non-ossifying fibroma
. Enchondroma

Correct Answer & Explanation

. Unicameral bone cyst

Explanation

The description is classic for a unicameral bone cyst (UBC), also known as a simple bone cyst. They typically appear as central metaphyseal lytic lesions in the proximal humerus or proximal femur of children. The presence of a small piece of fractured cortex resting at the bottom of the fluid-filled cyst is known as the 'fallen leaf' or 'fallen fragment' sign and is considered pathognomonic for a UBC.

Question 2814

Topic: Bone Tumors
A 9-year-old girl is evaluated for a leg length discrepancy and a progressive bowing deformity of her left femur. Radiographs show a 'shepherd's crook' deformity with ground-glass opacities in the proximal femur. Physical examination reveals multiple large café-au-lait spots with irregular 'coast of Maine' borders on her trunk. Which endocrinopathy is most commonly associated with her underlying condition?
. Precocious puberty
. Hypothyroidism
. Diabetes insipidus
. Hyperparathyroidism
. Cushing's disease

Correct Answer & Explanation

. Precocious puberty

Explanation

The patient has McCune-Albright syndrome, which is characterized by the classic triad of polyostotic fibrous dysplasia (producing the 'shepherd's crook' deformity and ground-glass appearance), café-au-lait macules with irregular borders, and hyperfunctioning endocrinopathies. The most common endocrine abnormality in this syndrome is gonadotropin-independent precocious puberty.

Question 2815

Topic: 10. Pathology and Oncology

A 28-year-old woman presents with a slow-growing, painful soft-tissue mass near her left knee joint. MRI reveals a deep mass in the popliteal fossa with focal areas of calcification. Core needle biopsy demonstrates a biphasic tumor consisting of both epithelial and spindle cell components. Which of the following is true regarding this specific pathology?

. It most commonly arises directly from the intra-articular synovial lining.
. It is driven by an underlying t(11;22) chromosomal translocation.
. It has a higher propensity to metastasize to regional lymph nodes compared to most other soft tissue sarcomas.
. It represents a benign, reactive proliferation of synovial tissue.
. Its primary treatment involves chemotherapy alone due to extreme radiosensitivity.

Correct Answer & Explanation

. It has a higher propensity to metastasize to regional lymph nodes compared to most other soft tissue sarcomas.

Explanation

The diagnosis is synovial sarcoma, which is characterized by a biphasic histology and often presents with calcifications on imaging near a joint. Despite its name, it rarely arises from the actual intra-articular synovium. Synovial sarcoma is notable for its higher rate of lymph node metastasis (up to 20%) compared to other soft tissue sarcomas. It is associated with the t(X;18) translocation, not t(11;22) which is seen in Ewing sarcoma.

Question 2816

Topic: 10. Pathology and Oncology

A 15-year-old boy presents with progressive thigh pain and swelling. Radiographs show a diaphyseal permeative lytic lesion in the femur with a prominent 'onion skin' periosteal reaction. Biopsy confirms sheets of uniform small round blue cells. What is the most common genetic translocation associated with this patient's underlying condition?

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

Correct Answer & Explanation

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

Explanation

The clinical scenario and imaging describe Ewing sarcoma, an aggressive pediatric bone tumor. It is characterized by the pathognomonic t(11;22)(q24;q12) chromosomal translocation in approximately 85-90% of cases. This translocation fuses the EWS gene on chromosome 22 with the FLI1 gene on chromosome 11, creating an aberrant transcription factor that drives tumorigenesis. The t(X;18) translocation is seen in synovial sarcoma. The t(2;13) translocation is characteristic of alveolar rhabdomyosarcoma. The t(12;16) translocation is found in myxoid liposarcoma. The t(9;22) translocation is seen in extraskeletal myxoid chondrosarcoma.

Question 2817

Topic: 10. Pathology and Oncology

A 28-year-old man presents with a slow-growing, painful mass near his knee joint that has been present for two years. MRI reveals a well-circumscribed soft tissue mass adjacent to, but not involving, the joint capsule, with focal calcifications. Biopsy demonstrates a biphasic pattern consisting of both epithelial and spindle cells. Which cytogenetic abnormality is pathognomonic for this tumor?

. t(12;16)(q13;p11)
. t(11;22)(q24;q12)
. t(X;18)(p11;q11)
. t(2;13)(q35;q14)
. t(1;2)(q25;q31)

Correct Answer & Explanation

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

Explanation

The tumor described is a Synovial Sarcoma. Despite its name, it rarely arises directly from the synovium but rather presents in juxta-articular soft tissues of young adults. It is cytogenetically defined by the t(X;18)(p11;q11) translocation, which results in the SYT-SSX fusion gene. Classic features include focal calcifications on radiographs (seen in about 30% of cases) and a biphasic histologic pattern. Options A, B, and D correspond to myxoid liposarcoma, Ewing sarcoma, and alveolar rhabdomyosarcoma, respectively.

Question 2818

Topic: 10. Pathology and Oncology
A 14-year-old girl undergoes neoadjuvant chemotherapy followed by wide surgical resection of a primary conventional osteosarcoma of the distal femur. Which of the following factors is the most powerful and reliable predictor of long-term overall survival for this patient?
. Tumor volume at initial presentation
. Histologic percentage of tumor necrosis in the resected specimen
. The specific combination of chemotherapy agents utilized
. Anatomic location of the primary tumor
. Patient age at the time of diagnosis

Correct Answer & Explanation

. Histologic percentage of tumor necrosis in the resected specimen

Explanation

In the management of high-grade osteosarcoma, the single most important prognostic factor for overall survival is the histologic response of the primary tumor to neoadjuvant chemotherapy, which is measured by the percentage of tumor necrosis in the resected specimen. A 'good response' is universally defined as 90% or greater tumor necrosis (often graded via the Huvos system). Patients achieving ≥90% necrosis have significantly higher long-term event-free and overall survival rates compared to poor responders (<90% necrosis).

Question 2819

Topic: 10. Pathology and Oncology

A 55-year-old man presents with progressive sacral pain and recent onset of bowel and bladder dysfunction. Imaging reveals a large, destructive midline mass centered in the sacrum. Biopsy demonstrates characteristic 'physaliferous' (bubbly) cells set in a myxoid stroma. Which of the following is the most appropriate definitive management strategy for this tumor?

. Intralesional curettage and cementation
. Neoadjuvant chemotherapy followed by intralesional excision
. Primary definitive external beam radiotherapy alone
. Wide surgical en bloc resection with negative margins
. Targeted immunotherapy with immune checkpoint inhibitors

Correct Answer & Explanation

. Wide surgical en bloc resection with negative margins

Explanation

The clinical and histologic findings are diagnostic of a Chordoma, a rare, slow-growing, locally aggressive malignant bone tumor arising from embryonic notochord remnants. Chordomas are notoriously resistant to conventional chemotherapy and standard-dose radiation therapy. Intralesional procedures invariably lead to high rates of local recurrence. Therefore, the gold standard for curative-intent treatment of a sacral chordoma is wide en bloc surgical resection with negative margins, balancing the oncologic outcome with the expected neurological deficits resulting from sacral root sacrifice.

Question 2820

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with a 3-month history of thigh pain and swelling. Radiographs reveal a permeative diaphyseal lesion in the femur with a 'periosteal onion-skin' reaction. Biopsy shows uniform small round blue cells. Which of the following chromosomal translocations is most characteristic of this condition?

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

Correct Answer & Explanation

. t(11;22)

Explanation

Ewing sarcoma is characterized by the t(11;22) chromosomal translocation, which results in the fusion of the EWS gene on chromosome 22 with the FLI1 gene on chromosome 11. t(9;22) is seen in some chondrosarcomas and chronic myelogenous leukemia. t(X;18) is pathognomonic for synovial sarcoma. t(12;16) is seen in myxoid liposarcoma, and t(2;13) is seen in alveolar rhabdomyosarcoma.

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