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10. Pathology and Oncology MCQs

Practice Set 137 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 2721

Topic: Bone Tumors
A 65-year-old man presents with generalized bone pain and a recent pathologic fracture of the proximal humerus. Laboratory studies show anemia, hypercalcemia, and renal insufficiency. Serum protein electrophoresis reveals a monoclonal spike. Which of the following is the most appropriate initial diagnostic imaging modality for staging his skeletal disease?
. Technetium-99m bone scan
. Whole-body low-dose CT (WBLDCT)
. Positron emission tomography (PET) scan
. Gadolinium-enhanced MRI of the humerus
. Single-photon emission computed tomography (SPECT)

Correct Answer & Explanation

. Whole-body low-dose CT (WBLDCT)

Explanation

Whole-body low-dose CT (WBLDCT) is now considered the standard of care and preferred initial imaging modality for detecting osteolytic bone lesions in multiple myeloma. Technetium-99m bone scans depend on osteoblastic activity, which is severely suppressed in myeloma, frequently leading to false-negative results.

Question 2722

Topic: Bone Tumors

A 14-year-old girl presents with pain and swelling in her right shoulder. Radiographs demonstrate an expansile, eccentric lytic lesion in the proximal humerus metaphysis with a thin sclerotic rim. MRI shows multiple fluid-fluid levels. The pathogenesis of this lesion is most strongly associated with a rearrangement involving which of the following genes?

. GNAS
. EXT1
. USP6
. RUNX2
. TP53

Correct Answer & Explanation

. USP6

Explanation

Primary aneurysmal bone cysts (ABCs) are true neoplasms characterized by translocations causing the upregulation of the USP6 gene on chromosome 17p13. GNAS mutations are seen in fibrous dysplasia; EXT1/EXT2 are associated with multiple hereditary exostoses; RUNX2 is associated with cleidocranial dysplasia; and TP53 is associated with Li-Fraumeni syndrome.

Question 2723

Topic: 10. Pathology and Oncology
A 55-year-old man presents with a constant, dull ache in his right hip that worsens at night. Radiographs reveal a radiolucent lesion in the right ilium with intralesional stippled calcifications and endosteal scalloping. Biopsy confirms a grade II (intermediate-grade) conventional chondrosarcoma. What is the most appropriate management?
. Intralesional curettage and bone grafting
. Wide surgical resection alone
. Wide surgical resection and adjuvant radiation therapy
. Neoadjuvant chemotherapy followed by wide surgical resection
. Primary radiation therapy

Correct Answer & Explanation

. Wide surgical resection alone

Explanation

Conventional chondrosarcomas are generally highly resistant to both chemotherapy and radiation therapy. The mainstay of treatment for intermediate (grade II) and high-grade (grade III) chondrosarcomas, as well as pelvic chondrosarcomas, is wide surgical resection. Intralesional curettage is generally reserved for benign cartilaginous lesions or select peripheral low-grade (grade I) atypical cartilaginous tumors in the appendicular skeleton.

Question 2724

Topic: 10. Pathology and Oncology

A 19-year-old man complains of severe right thigh pain that is worse at night and dramatically relieved by NSAIDs. Radiographs show a small radiolucent nidus surrounded by dense reactive sclerosis in the femoral diaphysis. If a biopsy of the nidus were performed, what would be the expected histologic finding?

. Cartilage-capped exostosis
. Small round blue cells with Homer-Wright rosettes
. Interlacing trabeculae of woven bone lined by prominent osteoblasts
. Sheets of lipid-laden macrophages
. Spindle cells arranged in a herringbone pattern

Correct Answer & Explanation

. Interlacing trabeculae of woven bone lined by prominent osteoblasts

Explanation

Osteoid osteoma is a benign bone-forming tumor. Histologically, the central nidus is highly vascular and consists of an anastomosing network of osteoid and woven bone trabeculae lined by prominent, single layers of plump, active osteoblasts.

Question 2725

Topic: Bone Tumors
A 9-year-old girl is evaluated for a limp and a discrepancy in leg length. Radiographs reveal a 'shepherd's crook' deformity of the proximal femur with a 'ground-glass' appearance. She also has irregularly bordered hyperpigmented skin macules and a history of precocious puberty. This condition is caused by a somatic activating mutation resulting in the overproduction of which intracellular signaling molecule?
. Cyclic AMP (cAMP)
. Cyclic GMP (cGMP)
. Inositol triphosphate (IP3)
. Tyrosine kinase
. Beta-catenin

Correct Answer & Explanation

. Cyclic AMP (cAMP)

Explanation

McCune-Albright syndrome consists of polyostotic fibrous dysplasia, café-au-lait spots, and endocrine abnormalities. It is caused by a somatic mutation in the GNAS gene, which encodes the stimulatory G protein alpha subunit (Gsα). This mutation results in constitutive activation of adenylyl cyclase and unregulated overproduction of intracellular cAMP.

Question 2726

Topic: 10. Pathology and Oncology

A 24-year-old woman presents with a slowly enlarging, painful mass around her left knee. MRI demonstrates a deeply seated, multilobulated soft-tissue mass in the popliteal fossa. Radiographs reveal focal stippled calcifications. Biopsy reveals a biphasic pattern of spindle cells and epithelial cells. What is the most common site of distant metastasis for this specific type of sarcoma?

. Bone
. Brain
. Liver
. Lungs
. Regional lymph nodes

Correct Answer & Explanation

. Lungs

Explanation

The diagnosis is synovial sarcoma, which frequently presents in periarticular regions of young adults, often shows calcifications on radiographs, and has a characteristic biphasic histologic pattern. The most common site of distant metastasis for synovial sarcoma, like most soft-tissue sarcomas, is the lungs. Although synovial sarcoma has a higher rate of regional lymph node metastasis than other sarcomas, the lungs remain the most common overall site.

Question 2727

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with a 3-month history of progressive thigh pain and swelling. Radiographs show a destructive diaphyseal lesion of the femur with a lamellated 'onion skin' periosteal reaction. A core needle biopsy reveals uniform sheets of small round blue cells with scant cytoplasm. Cytogenetic analysis of this tumor is most likely to show which of the following translocations?

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

Correct Answer & Explanation

. t(11;22)

Explanation

The clinical and radiographic presentation, along with the 'small round blue cell' histology, is classic for Ewing sarcoma. Ewing sarcoma is characterized by the t(11;22)(q24;q12) translocation, which results in the EWSR1-FLI1 fusion protein. t(9;22) is associated with chronic myelogenous leukemia or extraskeletal myxoid chondrosarcoma. t(X;18) is pathognomonic for synovial sarcoma. t(12;16) is seen in myxoid liposarcoma, and t(2;13) is characteristic of alveolar rhabdomyosarcoma.

Question 2728

Topic: 10. Pathology and Oncology
A 45-year-old man presents with a painful mass in his proximal humerus. Radiographs demonstrate a lytic lesion with intralesional 'popcorn' calcifications and endosteal scalloping involving greater than 2/3 of the cortical thickness. Biopsy confirms a grade II chondrosarcoma. Which of the following represents the most appropriate and definitive management?
. Neoadjuvant chemotherapy followed by wide resection
. Intralesional curettage and bone grafting
. Wide surgical resection alone
. Radiation therapy followed by wide resection
. Denosumab therapy followed by curettage

Correct Answer & Explanation

. Wide surgical resection alone

Explanation

Intermediate (grade II) and high-grade (grade III) chondrosarcomas are generally resistant to both chemotherapy and radiation therapy. The standard of care for these malignant cartilage tumors is wide surgical resection with negative margins. Intralesional curettage is reserved for benign cartilage lesions (like enchondromas) or select atypical cartilaginous tumors (grade I chondrosarcoma in the appendicular skeleton).

Question 2729

Topic: Bone Tumors

A 22-year-old man presents with a 6-month history of left knee pain that is significantly worse at night. The pain is dramatically relieved within 30 minutes of taking ibuprofen. Radiographs reveal a 1-cm radiolucent nidus surrounded by dense, reactive sclerotic bone in the proximal tibial diaphysis. Which of the following inflammatory mediators is most responsible for this classic pain pattern?

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

Correct Answer & Explanation

. Prostaglandin E2 (PGE2)

Explanation

The clinical scenario is classic for an osteoid osteoma. The intense night pain associated with osteoid osteomas is due to the local production of exceptionally high levels of prostaglandins, particularly Prostaglandin E2 (PGE2), by the nidus. Nonsteroidal anti-inflammatory drugs (NSAIDs) inhibit cyclooxygenase, effectively blocking PGE2 production and providing dramatic symptomatic relief.

Question 2730

Topic: Bone Tumors

A 12-year-old boy is found to have an incidental lesion in the proximal humerus during a workup for shoulder stiffness. Radiographs show a centrally located, well-circumscribed radiolucent lesion in the metaphysis with mild cortical thinning. If a diagnostic aspiration of this intact lesion is performed, which of the following fluid characteristics is most classically expected?

. High amylase content
. Frank, uncoagulated blood
. Clear or serosanguineous fluid with high levels of prostaglandins
. Clear yellow fluid with high cholesterol content
. Purulent fluid with high polymorphonuclear cells

Correct Answer & Explanation

. Clear or serosanguineous fluid with high levels of prostaglandins

Explanation

The radiographic description strongly suggests a unicameral (simple) bone cyst (UBC). Aspiration of an intact UBC typically yields clear or serosanguineous fluid. Biochemical analysis of this cyst fluid reliably demonstrates significantly elevated levels of prostaglandins (especially PGE2), alkaline phosphatase, interleukins, and nitrogen. Frank blood would be more characteristic of an aneurysmal bone cyst.

Question 2731

Topic: 10. Pathology and Oncology

A 28-year-old woman complains of a slowly enlarging, painful mass in her left foot over the past year. MRI reveals an indeterminate soft tissue mass, and plain radiographs demonstrate stippled calcifications within the substance of the mass. A core biopsy confirms synovial sarcoma. Which of the following represents the characteristic cytogenetic abnormality for this neoplasm?

. t(12;16)
. t(X;18)
. t(2;13)
. t(11;22)
. MDM2 gene amplification

Correct Answer & Explanation

. t(X;18)

Explanation

Synovial sarcoma classically harbors the t(X;18)(p11;q11) translocation, which results in the SYT-SSX fusion gene. This tumor often occurs in the extremities of young adults, particularly around the knee or in the foot/ankle. Despite its name, it rarely arises within the joint itself. Punctate calcifications on plain radiographs are seen in up to 30% of cases.

Question 2732

Topic: 10. Pathology and Oncology

A 68-year-old man with a known 15-year history of polyostotic Paget's disease presents with a 2-month history of rapidly worsening pain and swelling in his right thigh, a symptom notably different from his baseline. Radiographs demonstrate a destructive, mixed lytic and sclerotic lesion in the femoral diaphysis with a wide zone of transition, cortical breakthrough, and a soft tissue mass. What is the most likely diagnosis?

. Metastatic prostate cancer
. Osteosarcoma
. Chondrosarcoma
. Multiple myeloma
. Fibrosarcoma

Correct Answer & Explanation

. Osteosarcoma

Explanation

Malignant transformation occurs in less than 1% of patients with Paget's disease, but the risk increases with widespread polyostotic disease. The most common secondary malignancy arising in Pagetic bone is osteosarcoma (Paget's sarcoma). It typically presents in older adults with new, unrelenting pain and destructive radiographic changes. The prognosis is generally poor compared to primary osteosarcoma in young patients.

Question 2733

Topic: 10. Pathology and Oncology

A 9-year-old girl undergoes a biopsy of an expansile, eccentrically located, lytic metaphyseal lesion in her proximal tibia. The MRI demonstrates multiple fluid-fluid levels. Histopathology describes cavernous, blood-filled spaces lacking a true endothelial lining, separated by fibrous septa containing multinucleated giant cells. Which of the following genetic alterations is most specific to the primary pathogenesis of this lesion?

. GNAS1 mutation
. EXT1 mutation
. USP6 translocation
. TP53 mutation
. H3F3A mutation

Correct Answer & Explanation

. USP6 translocation

Explanation

The clinical, radiographic, and histologic findings are diagnostic of an aneurysmal bone cyst (ABC). Primary ABCs are now known to be true neoplasms, driven by translocations involving the USP6 gene on chromosome 17p13 (most commonly t(16;17)). The GNAS1 mutation is associated with fibrous dysplasia; EXT1 with osteochondromas; and H3F3A with giant cell tumors of bone.

Question 2734

Topic: 10. Pathology and Oncology
A 15-year-old boy completes a standard course of neoadjuvant multidrug chemotherapy (MAP: methotrexate, doxorubicin, cisplatin) for high-grade conventional osteosarcoma of the distal femur. He subsequently undergoes a wide surgical resection. The pathology report notes 95% tumor necrosis in the resected specimen. Which of the following best describes the clinical significance of this finding?
. It dictates the need to add radiation therapy postoperatively
. It is an unreliable metric, and overall survival correlates best with primary tumor volume
. It is the single most important prognostic factor for long-term overall survival
. It implies a higher risk of developing a secondary hematologic malignancy
. It indicates the need to immediately switch to a different chemotherapy regimen

Correct Answer & Explanation

. It is the single most important prognostic factor for long-term overall survival

Explanation

In the management of high-grade osteosarcoma, the degree of histologic tumor necrosis following neoadjuvant chemotherapy is widely recognized as the single most important prognostic factor for disease-free and overall survival. A 'good response' is classically defined as >90% tumor necrosis (Huvos grade III/IV), which correlates with a significantly higher survival rate compared to patients with a poor response (<90% necrosis).

Question 2735

Topic: 10. Pathology and Oncology

A 55-year-old man presents with an enlarging, painful mass in his proximal humerus. Radiographs show a lytic lesion with 'ring and arc' calcifications in the metadiaphysis. Biopsy demonstrates a hypercellular cartilaginous matrix with plump, binucleated chondrocytes and permeation into the surrounding lamellar bone. Which of the following gene mutations is most commonly associated with this primary bone tumor?

. EXT1
. USP6
. IDH1
. H3F3A
. GNAS

Correct Answer & Explanation

. IDH1

Explanation

The clinical, radiographic, and histologic presentation is classic for a conventional chondrosarcoma. Mutations in isocitrate dehydrogenase 1 and 2 (IDH1 and IDH2) are found in over 50% of central chondrosarcomas. EXT1/EXT2 mutations are associated with multiple hereditary exostoses (osteochondromas). H3F3A mutations are characteristically seen in giant cell tumors of bone and chondroblastomas. USP6 rearrangements are the hallmark of aneurysmal bone cysts. GNAS mutations are seen in fibrous dysplasia.

Question 2736

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with progressive knee pain and swelling for 3 months, accompanied by low-grade fevers. Radiographs of the distal femur reveal a permeative destructive lesion in the metadiaphysis with a prominent 'onion skin' periosteal reaction. Biopsy shows sheets of uniform small round blue cells. Immunohistochemistry is strongly positive for CD99. Which of the following chromosomal translocations is most characteristic of this tumor?

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

Correct Answer & Explanation

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

Explanation

The diagnosis is Ewing sarcoma, characterized by the clinical presentation in a young patient, permeative bone destruction with aggressive periostitis, and CD99-positive small round blue cells. The most common translocation is t(11;22)(q24;q12), which fuses the EWSR1 gene to the FLI1 gene, occurring in about 85% of cases. t(X;18) is pathognomonic for synovial sarcoma. t(2;13) is associated with alveolar rhabdomyosarcoma. t(12;16) is seen in myxoid liposarcoma. t(9;22) is the Philadelphia chromosome seen in chronic myeloid leukemia and occasionally extraskeletal myxoid chondrosarcoma.

Question 2737

Topic: Bone Tumors

A 19-year-old man complains of a dull, aching pain in his right thigh that consistently worsens at night but is profoundly relieved by ibuprofen. CT imaging reveals a 0.8-cm radiolucent nidus surrounded by dense reactive cortical sclerosis in the femoral diaphysis. If a surgical resection is performed, histological analysis of the central nidus would most likely reveal which of the following?

. A mature cartilage cap undergoing endochondral ossification
. Blood-filled cavernous spaces separated by fibrous septa lacking endothelial lining
. Sheets of atypical chondrocytes within an abundant myxoid matrix
. Whorls of bland spindle cells in a dense collagenous background
. Interlacing trabeculae of woven bone lined by prominent, plump osteoblasts

Correct Answer & Explanation

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

Explanation

The clinical history and CT findings are pathognomonic for an osteoid osteoma. Histologically, the central nidus is composed of highly vascularized connective tissue containing interlacing trabeculae of osteoid (woven bone) lined by prominent, benign-appearing osteoblasts. Option A describes an osteochondroma. Option B is characteristic of an aneurysmal bone cyst. Option C describes a myxoid chondrosarcoma. Option D is typical of a benign fibrous lesion such as a non-ossifying fibroma.

Question 2738

Topic: 10. Pathology and Oncology

A 28-year-old woman presents with a slow-growing, painful mass near her right knee that has been present for over two years. Radiographs show a soft-tissue mass with stippled calcifications. An MRI demonstrates a heterogeneous soft-tissue mass adjacent to, but distinct from, the joint space. A biopsy reveals a biphasic pattern consisting of epithelial-like glandular structures and a spindle cell stromal component. Which of the following genetic abnormalities is most specifically associated with this tumor?

. SYT-SSX fusion
. EWS-FLI1 fusion
. MDM2 amplification
. PAX3-FOXO1 fusion
. COL1A1-PDGFB fusion

Correct Answer & Explanation

. SYT-SSX fusion

Explanation

The clinical presentation (a slow-growing soft tissue mass in a young adult, often near a joint but extra-articular, with calcifications in about 30% of cases) and biphasic histology are classic for synovial sarcoma. Synovial sarcoma is characterized by the t(X;18)(p11;q11) translocation, fusing the SS18 (formerly SYT) gene with an SSX gene (SSX1, SSX2, or SSX4). MDM2 amplification is characteristic of well-differentiated and dedifferentiated liposarcomas. PAX3-FOXO1 is seen in alveolar rhabdomyosarcoma. COL1A1-PDGFB is found in dermatofibrosarcoma protuberans.

Question 2739

Topic: 10. Pathology and Oncology

A 60-year-old man presents with chronic low back pain and a recent onset of bowel and bladder dysfunction. MRI of the sacrum reveals a midline destructive lesion with a large pre-sacral soft-tissue component, displaying high signal intensity on T2-weighted images. A core needle biopsy reveals lobules of cells with abundant, bubbly, vacuolated cytoplasm arranged in cords. Immunohistochemistry for which of the following markers is most specific to confirm the diagnosis of this neoplasm?

. S-100 protein
. Epithelial Membrane Antigen (EMA)
. Cytokeratin
. Brachyury
. Smooth Muscle Actin (SMA)

Correct Answer & Explanation

. Brachyury

Explanation

The clinical scenario of a destructive sacral mass in an older adult causing neurologic compromise, combined with the histological finding of physaliferous (bubbly) cells, is highly characteristic of a chordoma. Chordomas are malignant tumors arising from embryonic notochord remnants. While they typically express S-100, EMA, and Cytokeratin, the nuclear expression of Brachyury (a transcription factor crucial for notochord development) is highly sensitive and specific for chordoma and serves as the diagnostic hallmark.

Question 2740

Topic: Bone Tumors

A 65-year-old woman is being evaluated for generalized bone pain, profound fatigue, and recent onset of hypercalcemia. Laboratory studies confirm a normocytic anemia, elevated serum creatinine, and a monoclonal spike on serum protein electrophoresis. Plain radiographs show multiple sharply marginated 'punched-out' lytic lesions in her skull and pelvis. If a technetium-99m bone scan is performed, which of the following findings is most likely?

. Diffuse uniformly increased radiotracer uptake throughout the axial skeleton
. Normal or 'cold' radiotracer uptake at the sites of the lytic lesions
. A 'superscan' appearance with absent renal radiotracer uptake
. Intensely increased focal uptake exclusively at the sites of the lytic lesions
. Asymmetric increased uptake isolated to the appendicular skeleton

Correct Answer & Explanation

. Normal or 'cold' radiotracer uptake at the sites of the lytic lesions

Explanation

The patient's presentation meets the CRAB criteria (Hypercalcemia, Renal failure, Anemia, Bone lesions) diagnostic of multiple myeloma. The lytic bone lesions in myeloma result from profound osteoclast activation mediated by myeloma cells, coupled with a striking suppression of osteoblast activity. Because technetium-99m methylene diphosphonate (Tc-99m MDP) bone scans rely on osteoblastic activity (new bone formation) to accumulate radiotracer, the purely osteolytic, osteoblast-suppressed lesions of multiple myeloma typically appear normal or 'cold' on a bone scan. Skeletal surveys or whole-body low-dose CT/MRI/PET are the preferred imaging modalities.

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