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10. Pathology and Oncology MCQs

Practice Set 213 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 4241

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with a painful diaphyseal lesion in the femur. Radiographs reveal an aggressive, permeative lytic lesion with an 'onion skin' periosteal reaction. A core needle biopsy is performed. Which of the following cytogenetic abnormalities is most closely associated with the likely diagnosis?

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

Correct Answer & Explanation

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

Explanation

The clinical and radiographic presentation is classic for Ewing sarcoma. The most common cytogenetic abnormality found in Ewing sarcoma 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 is associated with t(12;16). Alveolar rhabdomyosarcoma is associated with t(2;13).

Question 4242

Topic: Bone Tumors

A 65-year-old male presents with severe, atraumatic back pain and hypercalcemia. Radiographs show a 'punched-out' lytic lesion in the L3 vertebral body. Suspecting multiple myeloma, a workup is initiated. Which of the following imaging modalities is the LEAST sensitive for detecting additional skeletal lesions in this patient?

. Whole-body low-dose CT
. Positron emission tomography (PET-CT)
. Whole-body MRI
. Technetium-99m bone scintigraphy
. Skeletal survey radiography

Correct Answer & Explanation

. Technetium-99m bone scintigraphy

Explanation

Technetium-99m (Tc-99m) bone scans rely on osteoblastic activity. Multiple myeloma lesions are almost purely osteolytic and lack reactive osteoblastic bone formation; thus, they classically present as 'cold' or yield false-negative results on a bone scan. Low-dose CT, MRI, and PET are vastly superior imaging modalities for the detection of myeloma lesions.

Question 4243

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with a destructive diaphyseal bone lesion of the femur and an overlying soft tissue mass. Biopsy reveals uniform small round blue cells. Which specific chromosomal translocation is most classically characteristic of this tumor?

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

Correct Answer & Explanation

. t(11;22)

Explanation

Ewing sarcoma is a small round blue cell tumor typically found in the diaphysis of long bones in children and adolescents. It is classically associated with the t(11;22) translocation, which results in the oncogenic EWS-FLI1 fusion gene.

Question 4244

Topic: 10. Pathology and Oncology

A 60-year-old woman with metastatic breast cancer presents with a lytic lesion in the peritrochanteric region of the proximal femur, occupying half the cortical diameter, and complains of moderate pain with weight-bearing. Using the Mirels' scoring system, what is her score and the recommended management?

. Score 7; Observation with radiation
. Score 8; Observation with radiation
. Score 9; Prophylactic internal fixation
. Score 10; Prophylactic internal fixation
. Score 11; Amputation

Correct Answer & Explanation

. Score 10; Prophylactic internal fixation

Explanation

Her Mirels' score is exactly 10 (Proximal femur = 3, Lytic nature = 3, Size 1/3-2/3 = 2, Moderate pain = 2). A score of 9 or greater indicates an unacceptably high risk of impending pathologic fracture, making prophylactic internal fixation the highly recommended treatment.

Question 4245

Topic: 10. Pathology and Oncology

A 14-year-old boy presents with a destructive metaphyseal lesion of the distal femur. Biopsy reveals small round blue cells. Which of the following chromosomal translocations is most characteristic of this tumor?

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

Correct Answer & Explanation

. t(11;22)

Explanation

Ewing sarcoma is a small round blue cell tumor typically associated with the t(11;22) translocation. This specific genetic alteration results in the formation of the EWS-FLI1 fusion protein.

Question 4246

Topic: 10. Pathology and Oncology

A 15-year-old boy presents with knee pain and a blastic lesion in the distal femur with a periosteal "sunburst" reaction. Biopsy confirms osteosarcoma. What is the most significant prognostic factor for long-term survival in this patient?

. Tumor size at presentation
. Histologic subtype
. Percentage of tumor necrosis following neoadjuvant chemotherapy
. Initial serum alkaline phosphatase level
. Presence of a skip metastasis within the same bone

Correct Answer & Explanation

. Percentage of tumor necrosis following neoadjuvant chemotherapy

Explanation

The percentage of tumor necrosis following neoadjuvant chemotherapy is the most important prognostic factor for localized osteosarcoma. Greater than 90% necrosis indicates a good response and significantly better long-term survival.

Question 4247

Topic: 10. Pathology and Oncology

A 34-year-old female presents with severe pain in her thumb pulp, which is highly sensitive to cold, and excruciating point tenderness over the nail bed. There is a faint bluish discoloration under the nail plate. Radiographs show a small, smooth, scalloped radiolucency in the dorsal aspect of the distal phalanx. What is the most likely diagnosis?

. Enchondroma
. Inclusion cyst
. Glomus tumor
. Osteoid osteoma
. Squamous cell carcinoma

Correct Answer & Explanation

. Glomus tumor

Explanation

This is the classic presentation of a glomus tumor, a benign vascular hamartoma of the glomus body. The classic triad includes temperature sensitivity (cold intolerance), severe paroxysmal pain, and localized point tenderness. Radiographs may reveal a well-circumscribed, lytic, scalloped defect due to pressure erosion.

Question 4248

Topic: 10. Pathology and Oncology

A 5-year-old boy presents with an enlarged index finger. His parents note the finger has grown proportionally faster than the rest of his digits since birth. On exam, the finger is significantly larger in girth and length, with a palpable volar mass and radial deviation. Which of the following pathological findings is most characteristic of this condition?

. Hypertrophy of the flexor tendon
. Lipofibromatous hamartoma of the median nerve
. Multiple enchondromas
. Arteriovenous malformation
. Giant cell tumor of the tendon sheath

Correct Answer & Explanation

. Lipofibromatous hamartoma of the median nerve

Explanation

Macrodactyly of the hand is characterized by congenital overgrowth of all mesenchymal elements. It is most commonly associated with lipofibromatous hamartoma of the digital nerves (frequently within the median nerve distribution). The nerve becomes grossly enlarged due to extensive fibrofatty infiltration.

Question 4249

Topic: 10. Pathology and Oncology

A 15-year-old male presents with right knee pain and a palpable mass. Radiographs reveal a sunburst periosteal reaction in the distal femur. Biopsy confirms the production of malignant osteoid. The patient's family history is significant for a soft-tissue sarcoma in his father and early-onset breast cancer in his aunt. A mutation in which of the following genes is most likely associated with this patient's underlying condition?

. RB1
. TP53
. EXT1
. GNAS
. NF1

Correct Answer & Explanation

. TP53

Explanation

The patient's family history is highly suggestive of Li-Fraumeni syndrome, an autosomal dominant disorder caused by a germline mutation in the TP53 tumor suppressor gene. This syndrome classically predisposes individuals to a spectrum of malignancies, notably osteosarcoma, breast cancer, brain tumors, leukemia, and soft-tissue sarcomas. While RB1 mutations (familial retinoblastoma) also predispose to osteosarcoma, the family history of early-onset breast cancer and soft-tissue sarcoma strongly points to a TP53 mutation.

Question 4250

Topic: 10. Pathology and Oncology

A 12-year-old boy presents with progressive diaphyseal tibial pain, fevers, and an elevated ESR. Radiographs show a permeative lytic lesion with an 'onion-skin' periosteal reaction. Histopathology demonstrates sheets of uniform small round blue cells. Cytogenetic analysis is most likely to reveal which of the following translocations?

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

Correct Answer & Explanation

. t(11;22)

Explanation

The clinical, radiographic, and histologic presentation is classic for Ewing sarcoma. Over 85% of Ewing sarcomas are characterized by the t(11;22)(q24;q12) translocation, which results in the EWSR1-FLI1 fusion gene. t(X;18) is associated with synovial sarcoma, t(2;13) with alveolar rhabdomyosarcoma, t(12;16) with myxoid liposarcoma, and t(9;22) with CML (Philadelphia chromosome) and some forms of ALL.

Question 4251

Topic: 10. Pathology and Oncology

A 45-year-old man presents with chronic hip pain. Radiographs reveal a purely lytic lesion in the proximal femoral epiphysis. Biopsy demonstrates sheets of cells with abundant clear cytoplasm, distinct cytoplasmic membranes, and central nuclei scattered among hyaline cartilage. Woven bone formation is also noted. Which of the following is the most likely diagnosis?

. Chondroblastoma
. Clear cell chondrosarcoma
. Metastatic renal cell carcinoma
. Osteoblastoma
. Giant cell tumor of bone

Correct Answer & Explanation

. Clear cell chondrosarcoma

Explanation

Clear cell chondrosarcoma is a rare, low-grade malignant cartilage tumor that characteristically involves the epiphysis of long bones (most commonly the proximal femur or humerus) in adults (usually 30-50 years old). The presence of clear cells and variable woven bone production is classic. While chondroblastoma also occurs in the epiphysis and may contain areas resembling clear cells, it typically affects skeletally immature patients and exhibits 'chicken-wire' calcification.

Question 4252

Topic: Bone Tumors

A 10-year-old girl is evaluated for multiple bony prominences around her knees and wrists. Radiographs confirm multiple osteochondromas. Genetic testing reveals a mutation in the EXT1 gene. This mutation directly disrupts the biosynthesis of which of the following macromolecules?

. Hyaluronic acid
. Heparan sulfate
. Chondroitin sulfate
. Keratan sulfate
. Type II collagen

Correct Answer & Explanation

. Heparan sulfate

Explanation

Multiple hereditary exostoses (MHE) is an autosomal dominant condition caused by mutations in the EXT1 or EXT2 genes. These genes encode glycosyltransferases essential for the polymerization and biosynthesis of heparan sulfate. The resulting deficiency in heparan sulfate proteoglycans disrupts normal Indian hedgehog (Ihh) signaling at the growth plate, leading to the formation of osteochondromas.

Question 4253

Topic: Bone Tumors
A 9-year-old girl presents with a prominent limp and an apparent leg length discrepancy. Radiographs reveal a ground-glass appearance in the proximal femur with a 'shepherd's crook' deformity. Physical examination shows irregular, large pigmented skin patches with rough borders. What is the underlying molecular pathogenesis of this patient's bone lesions?
. Loss of function mutation in the NF1 gene
. Activating mutation in the GNAS gene causing persistent cAMP production
. Mutation in the FGFR3 gene resulting in constitutively active tyrosine kinase
. Defect in the CBFA1/RUNX2 transcription factor
. Inactivating mutation in the SQSTM1 gene

Correct Answer & Explanation

. Activating mutation in the GNAS gene causing persistent cAMP production

Explanation

The clinical picture describes McCune-Albright syndrome, defined by the triad of polyostotic fibrous dysplasia, 'coast of Maine' café-au-lait spots, and endocrinopathies (like precocious puberty). Fibrous dysplasia is caused by a somatic activating mutation in the GNAS gene, which encodes the alpha subunit of the stimulatory G protein (Gs). This leads to constitutively active adenylate cyclase, resulting in elevated intracellular cAMP and subsequent abnormal osteoblast differentiation.

Question 4254

Topic: 10. Pathology and Oncology

A 28-year-old female presents with a slowly enlarging, painless mass at the posterior aspect of her distal thigh. Radiographs reveal a heavily ossified, broad-based mass attached to the posterior cortex of the distal metaphysis of the femur. A radiolucent cleft is visible between portions of the mass and the underlying cortex. Cytogenetic analysis of the tumor is most likely to show amplification of which of the following genes?

. c-MYC
. HER2
. MDM2
. EWSR1
. RUNX2

Correct Answer & Explanation

. MDM2

Explanation

The clinical and radiographic presentation is classic for a parosteal osteosarcoma, a low-grade surface osteosarcoma typically arising from the posterior aspect of the distal femur. The 'string sign' (radiolucent cleft) is characteristic. These tumors consistently show supernumerary ring chromosomes containing amplified sequences of 12q13-15, which include the MDM2 and CDK4 genes. Amplification of MDM2 leads to degradation of the p53 tumor suppressor protein.

Question 4255

Topic: 10. Pathology and Oncology

A 24-year-old male presents with a dull ache in his left lower leg. Radiographs demonstrate a multi-loculated, expansile, eccentric lytic lesion in the anterior cortex of the tibial diaphysis. Biopsy reveals a biphasic tumor consisting of epithelial cells forming nests and tubular structures embedded in a fibrous stroma. Immunohistochemistry is expected to be strongly positive for which of the following markers?

. S-100
. Cytokeratin
. Vimentin only
. CD99
. Smooth muscle actin (SMA)

Correct Answer & Explanation

. Cytokeratin

Explanation

The presentation is classic for adamantinoma, a rare, low-grade malignant primary bone tumor with a striking predilection for the anterior tibial diaphysis. Histologically, it is a biphasic tumor characterized by islands of epithelial cells within a fibrous stroma. The epithelial component characteristically stains positive for cytokeratins (like AE1/AE3) and EMA. CD99 is associated with Ewing sarcoma, and S-100 with neural or cartilaginous tumors.

Question 4256

Topic: 10. Pathology and Oncology

A 62-year-old man presents with progressive constipation and saddle anesthesia. MRI of the pelvis reveals a large, lobulated, locally destructive mass replacing the sacrum. Histopathological examination shows cords of cells with abundant vacuolated cytoplasm in a myxoid background. Which immunohistochemical marker is highly specific for confirming the origin of this tumor?

. Chromogranin
. Desmin
. Brachyury
. CD34
. S-100

Correct Answer & Explanation

. Brachyury

Explanation

The clinical presentation and histology (physaliferous cells with vacuolated cytoplasm) are characteristic of a chordoma, a locally aggressive malignant tumor arising from notochord remnants. While chordomas often stain positive for S-100, cytokeratins, and EMA, nuclear expression of brachyury (a transcription factor vital for notochord development) is highly sensitive and specific for distinguishing chordoma from other clear cell or myxoid tumors (like chondrosarcoma).

Question 4257

Topic: 10. Pathology and Oncology

A 25-year-old male presents with a slowly growing soft tissue mass deep in the thigh near the knee joint. Radiographs show a soft tissue density with eccentric stippled calcifications. Biopsy demonstrates a biphasic spindle-cell and epithelial proliferation. Which of the following genetic alterations is diagnostic for this mass?

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

Correct Answer & Explanation

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

Explanation

Synovial sarcoma is characterized by the t(X;18)(p11;q11) translocation, which creates the SYT-SSX (SS18-SSX) fusion gene. It often occurs in young adults near large joints (especially the knee), though rarely involves the joint space itself. Up to 30% display calcifications on plain radiographs. Histologically, it can be biphasic (spindle and epithelial components) or monophasic (spindle cells only).

Question 4258

Topic: 10. Pathology and Oncology

A 6-year-old boy presents with back pain. Radiographs reveal 'vertebra plana' of T8. A CT-guided biopsy is performed. The lesion contains numerous histiocytes with folded, clefted nuclei (coffee-bean shape) accompanied by eosinophils. Electron microscopy reveals racket-shaped intracytoplasmic organelles. The neoplastic cells are most likely to express which of the following immunophenotypes?

. CD1a (+), Langerin (+), S100 (+)
. CD68 (+), CD163 (+), CD1a (-)
. Cytokeratin (+), EMA (+), Brachyury (+)
. CD99 (+), FLI-1 (+), NKX2.2 (+)
. CD34 (+), STAT6 (+), S100 (-)

Correct Answer & Explanation

. CD1a (+), Langerin (+), S100 (+)

Explanation

The clinical presentation (vertebra plana in a child) and histologic findings (coffee-bean nuclei, eosinophils, Birbeck granules on EM) are diagnostic of Langerhans Cell Histiocytosis (LCH). The characteristic immunophenotype for LCH cells is positive for S100, CD1a, and Langerin (CD207). CD68/CD163 positivity without CD1a suggests a non-Langerhans histiocytosis. CD99/FLI-1 is indicative of Ewing sarcoma.

Question 4259

Topic: 10. Pathology and Oncology

A 22-year-old female presents with multiple painless, hard nodules on her hands. Examination reveals several bluish, soft, compressible nodules on her forearm and hand. Radiographs show multiple central lytic lesions with stippled calcifications within the phalanges. This patient is at a significantly increased risk for developing which of the following malignancies?

. Osteosarcoma
. Chondrosarcoma
. Angiosarcoma
. Ewing sarcoma
. Multiple myeloma

Correct Answer & Explanation

. Chondrosarcoma

Explanation

The patient has Maffucci syndrome, characterized by the presence of multiple enchondromas (Ollier disease) combined with soft tissue hemangiomas (the bluish, compressible nodules). Patients with Maffucci syndrome carry a high risk (up to 100% in some series) of malignant transformation of an enchondroma into a secondary chondrosarcoma. They also have an increased risk of visceral malignancies, but chondrosarcoma is the most prominent skeletal risk. These syndromes are associated with somatic mosaic mutations in IDH1 or IDH2.

Question 4260

Topic: 10. Pathology and Oncology

A 19-year-old male complains of right thigh pain that is worse at night and dramatically improves with ibuprofen. Radiographs demonstrate a 1-cm radiolucent nidus surrounded by dense cortical sclerosis in the femoral diaphysis. Which of the following is true regarding the histopathology and pathophysiology of this lesion?

. The nidus is avascular and necrotic.
. It is histologically distinct from an osteoblastoma.
. The lesion produces high levels of prostaglandins.
. Malignant transformation to osteosarcoma is common if left untreated.
. The peripheral sclerotic bone contains the highest concentration of nerve fibers.

Correct Answer & Explanation

. The lesion produces high levels of prostaglandins.

Explanation

Osteoid osteoma is a benign bone-forming tumor characterized by a small (<1.5-2 cm) radiolucent nidus surrounded by reactive sclerosis. The nidus contains an interlacing network of osteoid trabeculae and highly vascularized stroma. It produces high levels of prostaglandins (especially PGE2), which mediate the intense pain and intense localized inflammatory response. NSAIDs block this production, providing dramatic relief. Histologically, it is identical to osteoblastoma (differentiated primarily by size >2cm). The nidus, not the sclerotic rim, contains abundant unmyelinated nerve fibers.

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