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10. Pathology and Oncology MCQs

Practice Set 226 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 4501

Topic: 10. Pathology and Oncology

A 55-year-old male with known renal cell carcinoma presents with progressive lower extremity weakness and bowel dysfunction.

Imaging reveals a destructive metastatic lesion at L3 causing mechanical collapse and severe canal stenosis. Operative decompression and stabilization are planned. What is the most critical preoperative step?

. Systemic administration of bisphosphonates
. Neoadjuvant external beam radiation
. Preoperative selective arterial embolization
. Initiation of high-dose corticosteroids only
. Placement of a temporary inferior vena cava filter

Correct Answer & Explanation

. Systemic administration of bisphosphonates

Explanation

Renal cell carcinoma metastases to the spine are highly vascular. Preoperative selective arterial embolization is strongly recommended to minimize life-threatening intraoperative blood loss.

Question 4502

Topic: 10. Pathology and Oncology

A 50-year-old diabetic male presents with severe unremitting back pain. MRI shows findings consistent with L4-L5 discitis and osteomyelitis. He is neurologically intact, hemodynamically stable, and blood cultures are negative. What is the most appropriate next step in management?

. Immediate initiation of broad-spectrum empiric intravenous antibiotics
. Immediate anterior surgical debridement and fusion
. CT-guided needle biopsy of the intervertebral disc space
. Prescription of oral antibiotics and a rigid TLSO brace
. Observation and repeat MRI in 4 weeks

Correct Answer & Explanation

. Immediate initiation of broad-spectrum empiric intravenous antibiotics

Explanation

In a stable, neurologically intact patient with suspected spondylodiscitis and negative blood cultures, a tissue diagnosis should be obtained via CT-guided biopsy before initiating antibiotics. Early empiric antibiotics can result in culture-negative biopsies, severely hindering targeted therapy.

Question 4503

Topic: 10. Pathology and Oncology

A 60-year-old patient with known systemic malignancy presents with an isolated spinal metastasis causing mechanical back pain but no acute neurological deficits. Which of the following primary tumor types is highly radiosensitive, often making radiation therapy the primary treatment modality over excisional surgery?

. Renal cell carcinoma
. Thyroid carcinoma
. Multiple myeloma
. Melanoma
. Gastrointestinal adenocarcinoma

Correct Answer & Explanation

. Renal cell carcinoma

Explanation

Hematopoietic tumors like multiple myeloma and lymphomas are highly radiosensitive. In the absence of gross mechanical instability or rapid neurological decline, they are typically managed primarily with radiation rather than aggressive surgical resection.

Question 4504

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with progressive pain in the diaphysis of the femur. Radiographs show a permeative, destructive lesion with a wide zone of transition and an 'onion-skin' periosteal reaction. Biopsy reveals uniform sheets of small round blue cells. Immunohistochemistry is strongly positive for CD99 in a membranous pattern.

Which of the following chromosomal translocations is most characteristic of this patient's diagnosis?

. t(11;22) resulting in EWS-FLI1 fusion
. t(X;18) resulting in SYT-SSX fusion
. t(12;16) resulting in FUS-DDIT3 fusion
. t(2;13) resulting in PAX3-FOXO1 fusion
. t(9;22) resulting in BCR-ABL fusion

Correct Answer & Explanation

. t(11;22) resulting in EWS-FLI1 fusion

Explanation

This is a classic presentation of Ewing Sarcoma. Characteristic features include diaphyseal location, onion-skin periosteal reaction, and sheets of small round blue cells that express CD99. The most common genetic alteration is the t(11;22)(q24;q12) translocation, which produces the EWS-FLI1 fusion protein. Synovial sarcoma is associated with t(X;18). Myxoid liposarcoma has t(12;16). Alveolar rhabdomyosarcoma has t(2;13).

Question 4505

Topic: 10. Pathology and Oncology

A 32-year-old female presents with knee pain. Radiographs demonstrate an eccentric, entirely lytic lesion located in the epiphysis of the proximal tibia, extending to the subchondral bone plate. Biopsy reveals a proliferation of uniform mononuclear cells interspersed with numerous osteoclast-like giant cells. What genetic mutation is most commonly associated with the pathogenesis of this tumor?

. USP6 translocation
. H3F3A mutation
. GNAS activating mutation
. IDH1 mutation
. EXT1 inactivating mutation

Correct Answer & Explanation

. USP6 translocation

Explanation

The clinical scenario describes a Giant Cell Tumor (GCT) of bone, classically presenting as an eccentric epiphyseal lesion in a skeletally mature patient. The neoplastic cells are the mononuclear cells, which express RANKL and recruit the reactive osteoclast-like giant cells. Over 90% of GCTs harbor a mutation in the H3F3A gene (typically G34W). USP6 translocations are seen in aneurysmal bone cysts.

Question 4506

Topic: 10. Pathology and Oncology

A 16-year-old girl presents with swelling in her distal femur. MRI reveals an expansile, multiloculated cystic lesion with prominent fluid-fluid levels. Core needle biopsy confirms multiple blood-filled spaces lacking an endothelial lining, surrounded by fibrous septa containing giant cells and woven bone.

Which of the following genetic alterations is the primary driver of this lesion?

. GNAS mutation
. USP6 translocation
. MDM2 amplification
. TP53 mutation
. H3F3B mutation

Correct Answer & Explanation

. GNAS mutation

Explanation

The lesion described is a primary Aneurysmal Bone Cyst (ABC). The presence of fluid-fluid levels on MRI is highly characteristic. While ABCs can be secondary to other tumors (like GCT, chondroblastoma, or osteoblastoma), primary ABCs are driven by rearrangements of the USP6 gene (most commonly t(16;17) fusing CDH11 to USP6).

Question 4507

Topic: 10. Pathology and Oncology

A 28-year-old male presents with a slow-growing, painful mass near his knee joint, though imaging confirms the lesion is extra-articular. Biopsy demonstrates a biphasic pattern consisting of sheets of uniform spindle cells and scattered glandular structures lined by cuboidal epithelial cells. Which of the following represents the characteristic genetic translocation for this soft tissue sarcoma?

. t(X;18) (SYT-SSX)
. t(11;22) (EWS-FLI1)
. t(12;16) (FUS-DDIT3)
. t(2;13) (PAX3-FOXO1)
. t(12;22) (EWS-ATF1)

Correct Answer & Explanation

. t(X;18) (SYT-SSX)

Explanation

This is the classic presentation and histology of a biphasic Synovial Sarcoma. Despite its name, it rarely involves the synovial tissue directly, but rather arises near joints. The pathognomonic translocation is t(X;18)(p11;q11), resulting in the SYT-SSX (or SS18-SSX) fusion gene.

Question 4508

Topic: 10. Pathology and Oncology

A 15-year-old boy is diagnosed with conventional high-grade osteosarcoma of the distal femur. Biopsy displays an overtly malignant stroma with high pleomorphism.

Regardless of whether the subtype is osteoblastic, chondroblastic, or fibroblastic, what is the absolute requisite histological hallmark required to establish this diagnosis?

. Production of malignant osteoid matrix directly by tumor cells
. Presence of anaplastic chondrocytes in a myxoid stroma
. Osteoclast-like giant cells evenly distributed among uniform mononuclear cells
. Proliferation of uniform spindle cells arranged in a herringbone pattern
. Nests of clear epithelioid cells separated by fibrous bands

Correct Answer & Explanation

. Production of malignant osteoid matrix directly by tumor cells

Explanation

The defining diagnostic feature of all conventional osteosarcomas is the production of osteoid (unmineralized bone matrix) directly by the malignant neoplastic cells. Without the demonstration of malignant osteoid, the diagnosis of osteosarcoma cannot be definitively made.

Question 4509

Topic: 10. Pathology and Oncology

A 55-year-old man presents with a painful mass in the proximal humerus. Radiographs show a lytic lesion with intralesional stippled and 'popcorn' calcifications. Biopsy demonstrates a cartilaginous matrix with moderate cellularity, atypical chondrocytes, binucleation, and permeation into surrounding marrow spaces. Which of the following genetic mutations is frequently observed in this neoplasm?

. EXT1 and EXT2 mutations
. IDH1 and IDH2 mutations
. GNAS mutation
. H3F3A mutation
. TP53 mutation

Correct Answer & Explanation

. EXT1 and EXT2 mutations

Explanation

The lesion is a conventional Chondrosarcoma. Mutations in isocitrate dehydrogenase 1 and 2 (IDH1 and IDH2) are frequently found in enchondromas and central chondrosarcomas. EXT1/2 mutations are characteristic of multiple hereditary exostoses (osteochondromas).

Question 4510

Topic: 10. Pathology and Oncology

A 65-year-old man presents with severe lower back pain. Radiographs reveal multiple punched-out lytic lesions in the vertebral bodies and skull. A technetium-99m bone scan is surprisingly normal (cold) in these affected areas.

Biopsy of a vertebral lesion would most likely reveal which of the following?

. Sheets of small round blue cells strongly expressing CD99
. Monoclonal proliferation of plasma cells expressing CD138
. Proliferation of neoplastic spindle cells with malignant osteoid
. Uniform giant cells with hyperchromatic nuclei
. Physaliferous cells with bubbly, vacuolated cytoplasm

Correct Answer & Explanation

. Sheets of small round blue cells strongly expressing CD99

Explanation

The presentation of punched-out lytic lesions with a cold bone scan (due to purely osteolytic activity with no osteoblastic reactive bone formation) in an older adult is classic for Multiple Myeloma. Histology will show a monoclonal proliferation of plasma cells, which characteristically express CD138 and CD38.

Question 4511

Topic: 10. Pathology and Oncology

A 12-year-old girl is evaluated for a limp and a leg length discrepancy. Radiographs demonstrate a well-defined 'ground-glass' appearance in the metaphysis and diaphysis of the proximal femur, accompanied by a shepherd's crook deformity. What is the underlying pathogenesis of this condition?

. Activating mutation of the GNAS gene resulting in increased intracellular cAMP
. Inactivating mutation of the EXT1 gene leading to disrupted heparan sulfate synthesis
. Translocation involving the USP6 gene leading to matrix metalloproteinase overexpression
. Overexpression of MDM2 causing inhibition of the p53 tumor suppressor pathway
. Mutation of the H3F3A gene altering histone methylation

Correct Answer & Explanation

. Activating mutation of the GNAS gene resulting in increased intracellular cAMP

Explanation

The clinical and radiographic features are diagnostic of Fibrous Dysplasia. The underlying cause is an activating missense mutation in the GNAS gene (typically occurring post-zygotically), which encodes the alpha subunit of the Gs G-protein. This leads to constitutive activation of adenylate cyclase and increased cAMP, causing abnormal proliferation and differentiation of skeletal progenitor cells.

Question 4512

Topic: 10. Pathology and Oncology

A 50-year-old man presents with chronic, insidious sacral pain and recent onset of bowel/bladder dysfunction. MRI reveals a large, destructive midline mass in the sacrum. Biopsy reveals lobules of large cells with prominent intracytoplasmic vacuoles (physaliferous cells) set within a rich myxoid stroma.

Which immunohistochemical marker is highly specific for this tumor?

. Brachyury
. CD99
. CD1a
. S100
. MUC4

Correct Answer & Explanation

. Brachyury

Explanation

The tumor described is a Chordoma, which originates from embryonic notochordal remnants. It most commonly occurs in the sacrum and the spheno-occipital region. The presence of 'physaliferous' (bubbly) cells is characteristic. Brachyury is a transcription factor essential for notochord development and serves as a highly sensitive and specific immunohistochemical marker for chordoma.

Question 4513

Topic: 10. Pathology and Oncology

A 25-year-old female presents with a deep-seated, slowly enlarging mass in the plantar aspect of her foot, which appears attached to the plantar aponeurosis. Biopsy reveals nests of clear and pale cells with prominent nucleoli. Immunohistochemistry is strongly positive for HMB-45, Melan-A, and S100. Which of the following translocations is diagnostic of this entity?

. t(12;22) resulting in EWS-ATF1
. t(X;18) resulting in SYT-SSX
. t(11;22) resulting in EWS-FLI1
. t(9;22) resulting in BCR-ABL
. t(2;13) resulting in PAX3-FOXO1

Correct Answer & Explanation

. t(12;22) resulting in EWS-ATF1

Explanation

The tumor is Clear Cell Sarcoma of soft tissue (also historically known as malignant melanoma of soft parts). Due to its neural crest differentiation, it stains positive for melanocytic markers (HMB-45, Melan-A, S100). The pathognomonic translocation is t(12;22)(q13;q12) which fuses the EWSR1 gene with ATF1.

Question 4514

Topic: 10. Pathology and Oncology

A 5-year-old boy presents with a painful lytic lesion in his parietal skull. Biopsy reveals a proliferation of mononuclear cells exhibiting folded, grooved nuclei (resembling coffee beans), admixed with a dense infiltrate of eosinophils. Electron microscopy of the lesional cells demonstrates intracytoplasmic 'tennis-racket' shaped Birbeck granules. These cells will characteristically express which of the following markers?

. CD1a, S100, and Langerin (CD207)
. CD99 and FLI1
. HMB-45 and Melan-A
. Cytokeratin and Epithelial Membrane Antigen (EMA)
. Smooth Muscle Actin (SMA) and Desmin

Correct Answer & Explanation

. CD1a, S100, and Langerin (CD207)

Explanation

The diagnosis is Langerhans Cell Histiocytosis (LCH). Classical histological features include grooved nuclei ('coffee bean' appearance), abundant background eosinophils (hence the older term 'eosinophilic granuloma'), and Birbeck granules on EM. The Langerhans cells are reliably positive for S100, CD1a, and Langerin (CD207). Approximately 50-60% of LCH cases harbor a BRAF V600E mutation.

Question 4515

Topic: 10. Pathology and Oncology

A 16-year-old boy presents with knee pain. Radiographs demonstrate a 2 cm lytic lesion with a thin sclerotic rim confined entirely to the epiphysis of the proximal tibia. Biopsy shows mononuclear cells, scattered osteoclast-like giant cells, and distinctive areas of 'chicken-wire' intercellular calcification. What is the underlying genetic mutation most commonly associated with this tumor?

. H3F3B mutation (typically K36M)
. GNAS mutation
. IDH1 mutation
. USP6 translocation
. EXT1 mutation

Correct Answer & Explanation

. H3F3B mutation (typically K36M)

Explanation

This is a Chondroblastoma, a rare benign cartilaginous tumor characteristically arising in the epiphysis of growing long bones. Histology features mononuclear chondroblasts, giant cells, and classic 'chicken-wire' calcifications. Genetically, over 90% have mutations in the histone H3.3 gene H3F3B (typically K36M), distinguishing it from Giant Cell Tumor of bone which predominantly harbors mutations in H3F3A (typically G34W).

Question 4516

Topic: 10. Pathology and Oncology

A 35-year-old man presents with chronic dull pain and swelling in the anterior mid-shaft of his leg. Radiographs reveal a multilocular, expansile, eccentric osteolytic lesion with a 'soap-bubble' appearance. Biopsy demonstrates a biphasic tumor with nests and cords of epithelial cells surrounded by a bland fibrous stroma.

This specific tumor occurs almost exclusively in which of the following bones?

. Tibia
. Femur
. Humerus
. Radius
. Calcaneus

Correct Answer & Explanation

. Tibia

Explanation

The diagnosis is Adamantinoma, a low-grade malignant bone tumor. It exhibits a biphasic histological pattern consisting of epithelial islands (positive for cytokeratins) within an osteofibrous stroma. Clinically, 80-90% of adamantinomas occur in the diaphysis of the tibia, typically in the anterior cortex.

Question 4517

Topic: Bone Tumors

A 22-year-old male presents with dull, aching pain in his mid-back that does not completely resolve with NSAIDs. Imaging reveals a 2.8 cm radiolucent lesion in the posterior elements of the L3 vertebra with an surrounding zone of reactive sclerosis. Histological evaluation shows a nidus of irregular, interconnected woven bone trabeculae lined by prominent osteoblasts, highly vascular loose connective tissue, and no atypical cells. Based on clinical and pathologic features, what is the most likely diagnosis?

. Osteoblastoma
. Osteoid osteoma
. Aneurysmal bone cyst
. Chondroblastoma
. Giant cell tumor of bone

Correct Answer & Explanation

. Osteoblastoma

Explanation

The histology described (woven bone trabeculae lined by osteoblasts in a vascular stroma) is identical for both osteoid osteoma and osteoblastoma. However, the distinction is made clinically and radiographically: osteoblastomas are larger (> 2.0 cm), often have a less dramatic response to NSAIDs/aspirin, and have a predilection for the posterior elements of the spine.

Question 4518

Topic: 10. Pathology and Oncology

A 65-year-old male presents with a large, deep intramuscular mass in his proximal thigh. Biopsy reveals two distinct components: one area shows well-differentiated liposarcoma (atypical lipomatous tumor) with lipoblasts, and abruptly transitioning adjacent areas show a high-grade, non-lipogenic pleomorphic sarcoma. Which of the following genetic alterations is the hallmark of this condition?

. Amplification of MDM2 and CDK4
. Amplification of MYC
. Amplification of HER2
. Amplification of N-MYC
. Mutation of TP53

Correct Answer & Explanation

. Amplification of MDM2 and CDK4

Explanation

The lesion is a Dedifferentiated Liposarcoma, which arises from a well-differentiated liposarcoma. Both well-differentiated and dedifferentiated liposarcomas are defined by a characteristic supernumerary ring or giant marker chromosome containing amplification of the 12q13-15 region, which includes the MDM2 and CDK4 genes. MDM2 overexpression inhibits p53 function.

Question 4519

Topic: 10. Pathology and Oncology

A 35-year-old female presents with chronic knee swelling, stiffness, and recurrent hemarthrosis without any history of trauma. MRI displays a nodular and frond-like synovial mass with extensive 'blooming' artifact on gradient-echo sequences due to hemosiderin deposition.

Which genetic alteration is primarily implicated in the pathogenesis of this disease?

. Translocation resulting in CSF1 overexpression
. Mutation of the H3F3A gene
. Amplification of the MDM2 gene
. Translocation of the SYT-SSX gene
. Mutation of the IDH1 gene

Correct Answer & Explanation

. Translocation resulting in CSF1 overexpression

Explanation

The patient has Pigmented Villonodular Synovitis (PVNS), now more accurately termed Tenosynovial Giant Cell Tumor (TGCT). The blooming artifact on MRI is classic for hemosiderin. The neoplastic driver is a t(1;2) translocation fusing the CSF1 gene to COL6A3, causing an overexpression of Colony Stimulating Factor 1 (CSF1). This acts in a paracrine fashion to attract a massive non-neoplastic inflammatory infiltrate of macrophages and multinucleated giant cells.

Question 4520

Topic: 10. Pathology and Oncology

A 40-year-old man presents with a painless, deep, intramuscular mass in the thigh. Biopsy shows a proliferation of small, uniform, round-to-oval cells set in an abundant myxoid stroma, accompanied by a prominent delicate arborizing 'chicken-wire' capillary network and scattered signet-ring lipoblasts. What is the characteristic translocation associated with this tumor?

. t(12;16) (FUS-DDIT3)
. t(2;13) (PAX3-FOXO1)
. t(11;22) (EWS-FLI1)
. t(X;18) (SYT-SSX)
. t(9;22) (EWS-CHN)

Correct Answer & Explanation

. t(12;16) (FUS-DDIT3)

Explanation

This is a Myxoid Liposarcoma. Typical histologic hallmarks include a myxoid matrix, a delicate 'chicken-wire' branching capillary vasculature, and lipoblasts. Over 90% of myxoid liposarcomas contain the t(12;16)(q13;p11) translocation, which fuses the FUS gene with the DDIT3 (CHOP) gene.

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