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10. Pathology and Oncology MCQs

Practice Set 224 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 4461

Topic: 10. Pathology and Oncology

A 14-year-old female presents with acute knee pain. MRI shows an eccentric, expansile metaphyseal lesion in the distal femur containing multiple fluid-fluid levels. Biopsy confirms an aneurysmal bone cyst (ABC). Which specific gene rearrangement is considered the primary neoplastic driver of this primary lesion?

. CSF1
. USP6
. GNAS
. MDM2
. EXT1

Correct Answer & Explanation

. CSF1

Explanation

Primary Aneurysmal Bone Cysts (ABCs) are now recognized as true neoplasms rather than reactive processes, primarily driven by a t(16;17) translocation leading to the upregulation of the USP6 oncogene.

Question 4462

Topic: 10. Pathology and Oncology

A 45-year-old man presents with chronic knee catching and swelling. Radiographs demonstrate dozens of small, uniform, radiopaque loose bodies confined to the joint space. This condition is primarily characterized by which of the following pathophysiologic processes?

. Malignant transformation of synovium
. Synovial hyperplasia secondary to trauma
. Metaplasia of the synovial membrane
. Deposition of calcium pyrophosphate
. Infection by atypical mycobacteria

Correct Answer & Explanation

. Malignant transformation of synovium

Explanation

Primary synovial chondromatosis involves the benign, self-limiting neoplastic metaplasia of the synovial membrane into cartilage, which detaches to form uniform loose bodies that may subsequently ossify.

Question 4463

Topic: 10. Pathology and Oncology

A 14-year-old girl presents with a rapidly enlarging, painful mass in her proximal tibia. Radiographs demonstrate an eccentric, expansile, purely lytic metaphyseal lesion with thinning of the surrounding cortex. MRI shows multiple fluid-fluid levels. Biopsy reveals blood-filled cystic spaces separated by fibrous septa containing giant cells, without significant atypia. Which of the following genetic alterations is the primary driver of this neoplasm?

. t(11;22) translocation
. GNAS1 missense mutation
. USP6 gene rearrangement
. IDH1 point mutation
. H3F3A mutation

Correct Answer & Explanation

. t(11;22) translocation

Explanation

This patient has a primary aneurysmal bone cyst (ABC). Primary ABCs are driven by rearrangements of the USP6 gene on chromosome 17p13, most commonly t(16;17), which leads to upregulation of matrix metalloproteinases.

Question 4464

Topic: 10. Pathology and Oncology

A 55-year-old man presents with chronic low back pain and recent-onset bowel and bladder incontinence. MRI demonstrates a destructive, lobulated midline mass arising from the sacrum. Biopsy reveals nests of large, vacuolated cells in a myxoid stroma. Which of the following immunohistochemical markers is most specific for diagnosing this lesion?

. S100 protein
. Brachyury
. CD99
. Smooth muscle actin
. Cytokeratin

Correct Answer & Explanation

. S100 protein

Explanation

The clinical presentation and presence of physaliferous (vacuolated) cells indicate a chordoma. Brachyury is a transcription factor critical for notochordal development and is a highly sensitive and specific nuclear marker for chordoma.

Question 4465

Topic: 10. Pathology and Oncology

A 16-year-old boy presents with right shoulder pain. Radiographs show a well-circumscribed lytic lesion in the proximal humeral epiphysis with central calcifications. Histologic examination demonstrates mononuclear cells, scattered osteoclast-like giant cells, and a 'chicken-wire' pattern of pericellular calcification. Which genetic mutation is classically associated with this tumor?

. H3F3B point mutation
. GNAS1 mutation
. EXT1 mutation
. BRAF V600E mutation
. MDM2 amplification

Correct Answer & Explanation

. H3F3B point mutation

Explanation

The lesion is a chondroblastoma, typically occurring in the epiphysis of young patients and featuring 'chicken-wire' calcifications. It is uniquely driven by a point mutation in the H3F3B gene (or less commonly H3F3A), altering histone H3.3.

Question 4466

Topic: 10. Pathology and Oncology

A 30-year-old man presents with anterior bowing of his lower leg. Radiographs reveal an eccentric, multiloculated 'soap-bubble' lytic lesion in the anterior diaphysis of the tibia. Biopsy shows a biphasic tumor with both epithelial and osteofibrous components. Which of the following is true regarding this pathology?

. It represents a benign developmental anomaly of the diaphysis
. It responds well to intralesional curettage and bone grafting
. The epithelial cells will stain positive for cytokeratin
. It is primarily treated with high-dose neoadjuvant radiation
. It shares a genetic origin with Ewing sarcoma

Correct Answer & Explanation

. It represents a benign developmental anomaly of the diaphysis

Explanation

Adamantinoma is a low-grade malignant bone tumor that almost exclusively occurs in the anterior tibial diaphysis. It is a biphasic tumor, and its epithelial component classically stains positive for cytokeratin.

Question 4467

Topic: 10. Pathology and Oncology

A 45-year-old woman presents with a deep-seated thigh mass. MRI shows a well-defined, multi-lobulated soft tissue mass. Histology demonstrates an abundant myxoid stroma, a rich branching capillary network resembling 'chicken-wire', and small lipoblasts. What is the characteristic chromosomal translocation associated with this sarcoma?

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

Correct Answer & Explanation

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

Explanation

Myxoid liposarcoma is characterized by a prominent plexiform capillary network ('chicken-wire' vascularity) and myxoid background. It is driven by the t(12;16) translocation, which fuses the FUS gene with the DDIT3 (CHOP) gene.

Question 4468

Topic: 10. Pathology and Oncology

A 24-year-old woman notes a painless, slow-growing mass on the posterior aspect of her distal thigh. Radiographs demonstrate a heavily ossified, broad-based mass attached to the posterior cortex of the distal femur, with a radiolucent cleft separating a portion of the tumor from the underlying bone (string sign). What molecular abnormality is the hallmark of this lesion?

. Loss of heterozygosity at the Rb locus
. Amplification of MDM2 and CDK4
. Translocation involving the USP6 gene
. Overexpression of RANK ligand
. Mutation of the p53 tumor suppressor gene

Correct Answer & Explanation

. Loss of heterozygosity at the Rb locus

Explanation

Parosteal osteosarcoma is a low-grade surface osteosarcoma arising from the posterior distal femur, classically showing a 'string sign' on radiographs. It is characterized genetically by ring chromosomes leading to amplification of MDM2 and CDK4.

Question 4469

Topic: 10. Pathology and Oncology

A 15-year-old boy presents with thigh pain and a destructive metaphyseal lesion in his distal femur. MRI reveals fluid-fluid levels, mimicking an aneurysmal bone cyst. However, biopsy of the septal walls demonstrates highly pleomorphic spindle cells producing fine, lace-like osteoid. Which of the following best describes the clinical behavior of this lesion?

. It is a benign, self-limiting process that often resolves post-fracture
. It is a low-grade malignancy effectively treated with wide excision alone
. It is a high-grade malignancy requiring neoadjuvant chemotherapy and wide resection
. It is an intermediate-grade tumor best treated with radiofrequency ablation
. It is highly sensitive to external beam radiation as primary therapy

Correct Answer & Explanation

. It is a benign, self-limiting process that often resolves post-fracture

Explanation

The diagnosis is telangiectatic osteosarcoma, which can mimic an ABC on imaging due to blood-filled cystic spaces. However, the presence of malignant cells producing osteoid in the septa confirms a high-grade malignancy requiring systemic chemotherapy and wide resection.

Question 4470

Topic: 10. Pathology and Oncology

A 12-year-old girl is evaluated for multiple bony deformities and numerous soft tissue masses. Radiographs reveal multiple enchondromas in her hands and long bones. Physical exam confirms the presence of several bluish, compressible soft tissue nodules representing hemangiomas. Patients with this specific syndrome are at the highest risk for developing which of the following malignancies?

. Osteosarcoma
. Chondrosarcoma
. Angiosarcoma
. Leukemia
. Fibrosarcoma

Correct Answer & Explanation

. Osteosarcoma

Explanation

This patient has Maffucci syndrome, distinguished from Ollier disease by the presence of soft tissue hemangiomas. Patients with Maffucci syndrome have a nearly 100% lifetime risk of malignant transformation, most commonly to chondrosarcoma.

Question 4471

Topic: 10. Pathology and Oncology

A 26-year-old man presents with a firm, painless nodule on the volar aspect of his wrist. Initial biopsy was read as a necrotizing granuloma, but the mass recurred and enlarged, and he now has palpable axillary lymphadenopathy. Repeat deep biopsy shows sheets of eosinophilic epithelial-appearing cells transitioning into spindle cells. Which immunohistochemical finding is diagnostic of this aggressive sarcoma?

. Strong nuclear positivity for Brachyury
. Loss of INI-1 (SMARCB1) expression
. Overexpression of MDM2
. Presence of the PAX3-FOXO1 fusion protein
. Positive staining for CD1a

Correct Answer & Explanation

. Strong nuclear positivity for Brachyury

Explanation

Epithelioid sarcoma typically affects the distal extremities of young adults, often mimics a benign granulomatous process, and has a high rate of lymphatic spread. Diagnosis is confirmed by the loss of INI-1 (SMARCB1) nuclear expression.

Question 4472

Topic: 10. Pathology and Oncology

A 48-year-old man presents with hip pain. Radiographs reveal a lytic lesion in the proximal femoral epiphysis with distinct sclerotic margins. Biopsy shows sheets of large cells with abundant clear cytoplasm and distinct cell membranes, interspersed with areas of hyaline cartilage. What is the most appropriate management for this lesion?

. Intralesional curettage with phenol adjuvant
. Neoadjuvant chemotherapy followed by wide resection
. Wide surgical resection
. Primary radiation therapy
. Observation and serial imaging

Correct Answer & Explanation

. Intralesional curettage with phenol adjuvant

Explanation

Clear cell chondrosarcoma typically presents in the epiphysis of long bones in adults (unlike chondroblastoma in teens). It is a low-grade malignant bone tumor that does not respond to chemotherapy or radiation; wide surgical resection is required.

Question 4473

Topic: 10. Pathology and Oncology

A 16-year-old girl is diagnosed with a high-grade soft tissue mass in her distal leg. Molecular testing demonstrates a t(2;13)(q35;q14) translocation resulting in a PAX3-FOXO1 fusion transcript. Based on these findings, which histological pattern is most likely to be seen on biopsy?

. Spindle cells arranged in a herringbone pattern
. Small round blue cells separated by fibrous septa into nest-like structures
. Biphasic glandular and spindle cell components
. Large pleomorphic cells with bizarre, multinucleated giant cells
. Signet-ring cells in a prominent myxoid background

Correct Answer & Explanation

. Spindle cells arranged in a herringbone pattern

Explanation

The PAX3-FOXO1 fusion is diagnostic for alveolar rhabdomyosarcoma. Histologically, it presents as a small round blue cell tumor with cells arranged in aggregates separated by fibrous septa, resembling pulmonary alveoli.

Question 4474

Topic: 10. Pathology and Oncology

A 32-year-old woman presents with recurrent hemorrhagic effusions of her left knee. MRI reveals a nodular synovial mass with significant blooming artifact on gradient-echo sequences. The pathogenesis of this disease is primarily driven by a t(1;2) translocation causing the overexpression of which of the following?

. RANK ligand
. Colony-stimulating factor 1 (CSF1)
. Fibroblast growth factor receptor 3 (FGFR3)
. Vascular endothelial growth factor (VEGF)
. Tumor necrosis factor alpha (TNF-alpha)

Correct Answer & Explanation

. RANK ligand

Explanation

Pigmented Villonodular Synovitis (PVNS), or Tenosynovial Giant Cell Tumor, is driven by a t(1;2) translocation that causes overexpression of CSF1. This attracts a dense infiltrate of non-neoplastic macrophages and giant cells, which form the bulk of the tumor.

Question 4475

Topic: Bone Tumors

A 19-year-old man presents with localized nighttime pain in his proximal femur that is dramatically relieved by ibuprofen. CT imaging reveals a 1-cm radiolucent nidus surrounded by dense reactive sclerosis. The nidus of this lesion is characterized by high levels of which of the following enzymes?

. Cyclooxygenase-2 (COX-2)
. Alkaline phosphatase
. Matrix metalloproteinase-9 (MMP-9)
. Tartrate-resistant acid phosphatase (TRAP)
. Lysyl oxidase

Correct Answer & Explanation

. Cyclooxygenase-2 (COX-2)

Explanation

Osteoid osteomas secrete high levels of prostaglandins (especially PGE2) secondary to robust COX-2 expression within the nidus osteoblasts. This pathogenesis explains the classic nocturnal pain that is highly responsive to NSAIDs.

Question 4476

Topic: 10. Pathology and Oncology

A 35-year-old man with a known history of Neurofibromatosis type 1 (NF-1) presents with rapid enlargement and new-onset severe resting pain in a long-standing, palpable thigh mass. A biopsy confirms a high-grade spindle cell sarcoma. Which genetic event is most strongly associated with the malignant transformation of his pre-existing lesion?

. Loss of the APC tumor suppressor gene
. Acquisition of the t(X;18) translocation
. Inactivation of CDKN2A or p53
. Amplification of the c-MYC oncogene
. Mutation in the GNAS1 gene

Correct Answer & Explanation

. Loss of the APC tumor suppressor gene

Explanation

Patients with NF-1 have plexiform neurofibromas that can undergo malignant transformation to Malignant Peripheral Nerve Sheath Tumors (MPNSTs). This transformation is typically driven by secondary genetic hits, most notably the loss of CDKN2A or p53.

Question 4477

Topic: 10. Pathology and Oncology
A 14-year-old boy completes neoadjuvant chemotherapy and undergoes a wide resection of a conventional osteosarcoma in his distal femur. Pathological analysis of the resected specimen is performed. According to the Rosen grading system, what histological finding in the resected specimen is the most powerful predictor of long-term survival?
. Absence of lymphovascular invasion
. Greater than 90% tumor necrosis
. Complete encapsulation of the tumor by a fibrous pseudocapsule
. Differentiation predominantly into chondroblastic rather than osteoblastic elements
. Presence of a dense lymphocytic infiltrate at the tumor margins

Correct Answer & Explanation

. Greater than 90% tumor necrosis

Explanation

The most important prognostic factor for conventional osteosarcoma following neoadjuvant chemotherapy is the percentage of tumor necrosis in the resection specimen. Necrosis greater than 90% (Huvos Grade III/IV) indicates a good response and correlates with improved survival.

Question 4478

Topic: 10. Pathology and Oncology

A 22-year-old man presents with an eccentric, radiolucent lesion in the proximal tibial metaphysis with a well-defined sclerotic rim. Biopsy reveals a lobular architecture with stellate and spindle cells embedded in an abundant myxoid and chondroid background. Multinucleated giant cells are present at the lobular peripheries. Which diagnosis is most consistent with these findings?

. Chondroblastoma
. Chondromyxoid fibroma
. Enchondroma
. Non-ossifying fibroma
. Myxoid chondrosarcoma

Correct Answer & Explanation

. Chondroblastoma

Explanation

Chondromyxoid fibroma is a rare benign bone tumor presenting as an eccentric metaphyseal lesion with sclerotic margins. Histologically, it features a characteristic lobular pattern with stellate cells in a myxochondroid background and osteoclast-like giant cells at the periphery.

Question 4479

Topic: Bone Tumors
A 9-year-old boy with multiple café-au-lait macules with irregular borders ('coast of Maine') presents with a limp. Radiographs demonstrate a classic 'shepherd’s crook' deformity of the proximal femur with a ground-glass appearance of the medullary canal. The fundamental cellular defect in this condition leads to which intracellular abnormality?
. Decreased intracellular calcium
. Constitutive activation of adenylyl cyclase leading to elevated cAMP
. Inhibition of the mTOR pathway
. Excessive accumulation of glycogen
. Defective assembly of type I collagen triple helices

Correct Answer & Explanation

. Constitutive activation of adenylyl cyclase leading to elevated cAMP

Explanation

McCune-Albright syndrome features polyostotic fibrous dysplasia, café-au-lait spots, and endocrinopathies. It is caused by a somatic activating mutation in GNAS1, causing constitutive adenylyl cyclase activity and elevated intracellular cAMP, impairing normal osteoblast differentiation.

Question 4480

Topic: 10. Pathology and Oncology

A 58-year-old male with a history of metastatic renal cell carcinoma (RCC) presents with severe mechanical back pain and progressive paraparesis. MRI reveals high-grade epidural spinal cord compression at T8 from a metastatic lesion, but the spine is mechanically stable. According to the NOMS (Neurologic, Oncologic, Mechanical, and Systemic) framework, what is the most appropriate management?

. Conventional external beam radiation therapy (cEBRT) alone
. Stereotactic body radiation therapy (SBRT) alone
. Posterior separation surgery followed by SBRT
. En bloc resection of the T8 vertebra
. Systemic chemotherapy alone

Correct Answer & Explanation

. Conventional external beam radiation therapy (cEBRT) alone

Explanation

Renal cell carcinoma is traditionally considered a radioresistant tumor, meaning it does not respond well to conventional external beam radiation therapy (cEBRT). While Stereotactic body radiation therapy (SBRT) can overcome radioresistance, it cannot be safely administered to a target immediately adjacent to the spinal cord without causing radiation myelopathy. Therefore, in the presence of high-grade epidural spinal cord compression, the appropriate NOMS-guided treatment is 'separation surgery' (decompression of the cord to create a safe margin) followed by postoperative SBRT.

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