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10. Pathology and Oncology MCQs

Practice Set 288 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 5741

Topic: Bone Tumors

A 25-year-old woman complains of night pain in her tibia that is dramatically relieved by NSAIDs. Radiographs show a small radiolucent nidus surrounded by dense reactive sclerosis. Which of the following substances is produced in abnormally high amounts by the nidus?

. Tumor necrosis factor-alpha
. Interleukin-1
. Prostaglandin E2
. Vascular endothelial growth factor
. Matrix metalloproteinase-9

Correct Answer & Explanation

. Prostaglandin E2

Explanation

The clinical picture describes an osteoid osteoma. The nidus secretes abnormally high levels of Prostaglandin E2 (PGE2), which mediates the characteristic night pain. NSAIDs provide dramatic relief by inhibiting cyclooxygenase and subsequent PGE2 synthesis.

Question 5742

Topic: 10. Pathology and Oncology

A 15-year-old boy presents with a painful mass around his distal femur. Biopsy reveals malignant spindle cells producing osteoid. Which of the following genetic mutations is most commonly associated with the pathogenesis of this tumor?

. t(11;22) translocation
. t(X;18) translocation
. Inactivation of the RB1 and TP53 genes
. Amplification of MDM2 and CDK4
. t(2;13) translocation

Correct Answer & Explanation

. Inactivation of the RB1 and TP53 genes

Explanation

Conventional high-grade osteosarcoma is highly associated with mutations in tumor suppressor genes, specifically RB1 and TP53 (the latter associated with Li-Fraumeni syndrome). Amplification of MDM2 and CDK4 is characteristic of parosteal and low-grade central osteosarcomas. Ewing sarcoma features t(11;22), Synovial sarcoma features t(X;18), and Alveolar rhabdomyosarcoma features t(2;13).

Question 5743

Topic: 10. Pathology and Oncology

A 12-year-old girl presents with a destructive, permeative diaphyseal lesion in her fibula with an 'onion skin' periosteal reaction. Histology shows sheets of uniform small round blue cells. Immunohistochemical staining of this tumor would most likely be strongly positive for which of the following markers?

. S-100
. Desmin
. CD99 (MIC2)
. Cytokeratin
. MyoD1

Correct Answer & Explanation

. CD99 (MIC2)

Explanation

The patient has Ewing sarcoma, a highly malignant small round blue cell tumor. It is characterized by the t(11;22) translocation resulting in the EWS-FLI1 fusion protein, and is strongly positive for the cell surface glycoprotein CD99 (MIC2) on immunohistochemistry. S-100 is for neural crest tumors/melanoma; Desmin and MyoD1 are for rhabdomyosarcoma; Cytokeratin is typically for carcinomas and occasionally synovial sarcoma.

Question 5744

Topic: 10. Pathology and Oncology

A 25-year-old female presents with a slow-growing, painless mass on the posterior aspect of her distal femur. Radiographs reveal a heavily ossified, broad-based mass originating from the cortex with a 'string sign' (a thin radiolucent line separating the tumor from the cortex). Molecular analysis of the biopsy specimen is most likely to demonstrate amplification of which of the following genes?

. EWS-FLI1
. MDM2
. EXT1
. GNAS
. RUNX2

Correct Answer & Explanation

. MDM2

Explanation

The clinical and radiographic presentation is classic for a parosteal osteosarcoma (posterior distal femur, heavily ossified, string sign). Parosteal osteosarcoma is a low-grade surface osteosarcoma characterized molecularly by ring chromosomes and amplification of the MDM2 and CDK4 genes on chromosome 12q13-15.

Question 5745

Topic: 10. Pathology and Oncology

A 35-year-old male undergoes arthroscopy for a recurrent, atraumatic, bloody effusion of the knee. Pathology reveals hyperplastic synovium with hemosiderin-laden macrophages and multinucleated giant cells. Which genetic alteration is the primary driver of this condition?

. Translocation t(11;22)
. Translocation t(1;2) causing overexpression of colony-stimulating factor 1 (CSF1)
. Mutation in the beta-catenin gene
. MDM2 gene amplification
. Activating mutation of the GNAS gene

Correct Answer & Explanation

. Translocation t(1;2) causing overexpression of colony-stimulating factor 1 (CSF1)

Explanation

The diagnosis is Pigmented Villonodular Synovitis (PVNS), now more accurately termed Tenosynovial Giant Cell Tumor (TGCT). The pathogenesis is driven by a t(1;2) translocation that fuses the CSF1 gene to the COL6A3 promoter, leading to an overproduction of CSF1, which acts as a chemoattractant for macrophages (giant cells).

Question 5746

Topic: 10. Pathology and Oncology

A 4-year-old girl is evaluated for short stature, cranial nerve palsies, and recurrent fractures. Radiographs reveal uniformly dense, 'marble-like' bones lacking a medullary canal. The most common malignant (infantile) autosomal recessive form of this disease is caused by a genetic defect leading to the loss of function of which enzyme?

. Tartrate-resistant acid phosphatase (TRAP)
. Cathepsin K
. Carbonic anhydrase II
. Alkaline phosphatase
. Matrix metalloproteinase-9 (MMP-9)

Correct Answer & Explanation

. Carbonic anhydrase II

Explanation

The patient has Osteopetrosis, a disease of defective osteoclast function. The autosomal recessive (malignant) form is most commonly caused by a mutation in the TCIRG1 gene (vacuolar proton pump) or Carbonic Anhydrase II. Carbonic anhydrase II is essential for generating the protons (H+) that are pumped across the ruffled border to acidify the resorption pit and dissolve bone mineral.

Question 5747

Topic: 10. Pathology and Oncology

A 28-year-old male presents with anterior tibial pain and a palpable mass. Radiographs show a multi-loculated, eccentric, lytic lesion with a 'soap bubble' appearance in the tibial diaphysis. Biopsy reveals nests of cells in a fibrous stroma. Immunohistochemical staining of the tumor cells will be strongly positive for which of the following markers?

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

Correct Answer & Explanation

. Cytokeratin

Explanation

The clinical and radiographic presentation is classic for an adamantinoma, a rare low-grade malignant bone tumor that almost exclusively occurs in the anterior tibial diaphysis. Uniquely for a primary bone tumor, adamantinoma has an epithelial origin (or exhibits epithelial differentiation) and stains strongly positive for epithelial markers such as cytokeratin.

Question 5748

Topic: 10. Pathology and Oncology

A 12-year-old male presents with thigh pain, fever, and weight loss. Radiographs demonstrate a diaphyseal permeative lesion in the femur with a prominent "onion-skin" periosteal reaction. Biopsy reveals small, round blue cells. What is the most common cytogenetic abnormality associated with 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 classically associated with the t(11;22) chromosomal translocation. This specific genetic alteration results in the formation of the EWS-FLI1 fusion protein, which acts as an aberrant transcription factor driving tumor progression.

Question 5749

Topic: 10. Pathology and Oncology

A 60-year-old male presents with a progressively painful mass in the proximal femur. Radiographs show a bulky lytic lesion with intralesional "popcorn" calcifications and extensive endosteal scalloping. Biopsy confirms a grade II conventional chondrosarcoma. What is the most appropriate primary management?

. Intralesional curettage and bone grafting
. Neoadjuvant chemotherapy followed by wide resection
. Wide surgical resection alone
. Radiation therapy alone
. Radiofrequency ablation

Correct Answer & Explanation

. Wide surgical resection alone

Explanation

Conventional chondrosarcomas are notoriously resistant to both chemotherapy and radiation therapy due to their poor vascularity and slow growth rate. The gold standard for curative treatment is wide surgical resection.

Question 5750

Topic: 10. Pathology and Oncology

A 30-year-old woman presents with isolated knee pain. Radiographs reveal a 4 cm eccentric, purely lytic epiphyseal lesion in the proximal tibia extending to the subchondral bone, lacking a sclerotic margin. Histology confirms multinucleated giant cells. Which of the following is the standard initial surgical treatment?

. Neoadjuvant chemotherapy and wide resection
. Intralesional curettage and high-speed burring with local adjuvants
. Wide en bloc resection and endoprosthetic reconstruction
. Primary radiation therapy
. Observation and protected weight-bearing

Correct Answer & Explanation

. Intralesional curettage and high-speed burring with local adjuvants

Explanation

Giant cell tumors of bone are locally aggressive, benign lesions classically located in the epiphysis. The standard treatment is extended intralesional curettage using a high-speed burr, combined with local adjuvants (phenol, liquid nitrogen, PMMA) to reduce recurrence rates.

Question 5751

Topic: 10. Pathology and Oncology

Shortly after the induction of general anesthesia with succinylcholine, a trauma patient develops severe tachycardia, masseter muscle rigidity, and a rapidly rising core temperature. What is the molecular basis of this life-threatening complication?

. Acetylcholinesterase deficiency at the neuromuscular junction
. Defective ryanodine receptors causing excessive sarcoplasmic calcium release
. Autoantibodies against presynaptic voltage-gated calcium channels
. Toxic inhibition of the sodium-potassium ATPase pump
. Mutation in the slow-twitch myosin heavy chain gene

Correct Answer & Explanation

. Defective ryanodine receptors causing excessive sarcoplasmic calcium release

Explanation

Malignant hyperthermia is a severe pharmacogenetic disorder linked to mutations in the ryanodine receptor (RYR1) gene. Exposure to trigger anesthetics causes an uncontrolled release of calcium from the sarcoplasmic reticulum, resulting in sustained muscle contraction and fatal hypermetabolism.

Question 5752

Topic: 10. Pathology and Oncology

A 16-year-old boy complains of aching right leg pain that predictably awakens him at night but is completely relieved by ibuprofen. Radiographs reveal a 0.8 cm radiolucent nidus surrounded by dense reactive sclerosis in the tibial diaphysis. What is the primary chemical mediator responsible for this distinct pain pattern?

. Interleukin-1 (IL-1)
. Tumor necrosis factor-alpha (TNF-alpha)
. Prostaglandin E2 (PGE2)
. Leukotriene B4 (LTB4)
. Substance P

Correct Answer & Explanation

. Prostaglandin E2 (PGE2)

Explanation

Osteoid osteomas are benign, bone-forming tumors characterized by a high concentration of cyclooxygenase-2 (COX-2) enzymes within the central nidus. This leads to abundant, localized production of Prostaglandin E2, which causes the classic night pain that is exquisitely sensitive to NSAIDs.

Question 5753

Topic: 10. Pathology and Oncology

A 52-year-old female sustains a pathologic fracture of her proximal humerus. Radiographs show a well-defined lytic lesion. Laboratory results show hypercalcemia, hypophosphatemia, and elevated parathyroid hormone. Biopsy of the lesion would most likely reveal which of the following?

. Malignant spindle cells producing osteoid
. Hemosiderin-laden macrophages and multinucleated giant cells
. Atypical plasma cells with eccentric nuclei
. Small round blue cells with Homer-Wright rosettes
. Sheets of uniform polygonal cells with clear cytoplasm

Correct Answer & Explanation

. Hemosiderin-laden macrophages and multinucleated giant cells

Explanation

The clinical picture describes primary hyperparathyroidism presenting with a brown tumor. Histologically, brown tumors are characterized by clusters of osteoclast-like multinucleated giant cells in a highly vascular stroma with abundant hemosiderin deposition.

Question 5754

Topic: 10. Pathology and Oncology

A 12-year-old boy presents with an expanding mass in the diaphysis of his femur. Radiographs show a permeative destructive lesion with an "onion-skin" periosteal reaction. Cytogenetics are most likely to reveal which of the following translocations?

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

Correct Answer & Explanation

. t(11;22)

Explanation

Ewing sarcoma is classically associated with the t(11;22) translocation, resulting in the EWS-FLI1 fusion protein. It typically presents in the diaphysis of long bones in children with a permeative pattern and onion-skin periosteal reaction.

Question 5755

Topic: Bone Tumors

A 19-year-old male complains of severe, aching pain in his right thigh that is worse at night and dramatically relieved by ibuprofen. Radiographs demonstrate a sclerotic area with a 5 mm radiolucent nidus in the femoral cortex. Which of the following is the predominant cell type responsible for producing the prostaglandin E2 (PGE2) in this lesion?

. Osteoclasts
. Osteoblasts
. Chondrocytes
. Macrophages
. Fibroblasts

Correct Answer & Explanation

. Osteoblasts

Explanation

The diagnosis is an osteoid osteoma. The nidus contains numerous active osteoblasts that produce high levels of PGE2, causing the characteristic nocturnal pain that responds exquisitely to NSAIDs.

Question 5756

Topic: 10. Pathology and Oncology

A 16-year-old boy presents with aching night pain in his right thigh that is completely relieved by ibuprofen. Imaging shows a 1 cm radiolucent nidus surrounded by intense reactive sclerosis in the femoral diaphysis. The nidus secretes high levels of which of the following substances?

. Prostaglandin E2
. Interleukin-1
. Tumor necrosis factor-alpha
. Bone morphogenetic protein-2
. Fibroblast growth factor-23

Correct Answer & Explanation

. Prostaglandin E2

Explanation

Osteoid osteomas present classically with nocturnal pain relieved by NSAIDs. This is due to the high levels of Prostaglandin E2 (PGE2) secreted by the osteoblasts within the tumor nidus, which NSAIDs directly inhibit.

Question 5757

Topic: 10. Pathology and Oncology

A 12-year-old boy presents with a painful, swollen mid-thigh. Radiographs show a permeative diaphyseal lesion with an 'onion-skin' periosteal reaction. A biopsy confirms a small round blue cell tumor. Which of the following chromosomal translocations is most strongly associated with this diagnosis?

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

Correct Answer & Explanation

. t(11;22)

Explanation

The clinical, radiographic, and histologic findings are diagnostic for Ewing sarcoma. Over 90% of Ewing sarcomas are characterized by the t(11;22)(q24;q12) translocation, creating the EWS-FLI1 fusion protein.

Question 5758

Topic: 10. Pathology and Oncology

In the multimodal treatment of high-grade osteosarcoma, which of the following factors represents the single most important prognostic indicator for long-term patient survival?

. Initial tumor volume at presentation
. Percentage of tumor necrosis following neoadjuvant chemotherapy
. Presence of a pathologic fracture at diagnosis
. Age of the patient at the time of diagnosis
. Anatomical location of the primary tumor

Correct Answer & Explanation

. Percentage of tumor necrosis following neoadjuvant chemotherapy

Explanation

The percentage of tumor necrosis observed in the resected specimen after neoadjuvant chemotherapy is the most significant prognostic factor for long-term survival in osteosarcoma. A 'good response' is classically defined as >90% tumor necrosis.

Question 5759

Topic: 10. Pathology and Oncology

A 15-year-old boy presents with a destructive diaphyseal lesion of the femur with a 'periosteal onion skin' reaction. Cytogenetic analysis of the biopsy is most likely to reveal which of the following translocations?

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

Correct Answer & Explanation

. t(11;22)

Explanation

The clinical and radiographic presentation is classic for Ewing sarcoma. The most common cytogenetic abnormality in Ewing sarcoma is the t(11;22) translocation, creating the pathognomonic EWS-FLI1 fusion protein.

Question 5760

Topic: 10. Pathology and Oncology
According to the Enneking surgical staging system for malignant musculoskeletal tumors, a high-grade osteosarcoma localized entirely within the medullary canal of the distal femur with no metastases is classified as:
. Stage IA
. Stage IB
. Stage IIA
. Stage IIB
. Stage III

Correct Answer & Explanation

. Stage IIA

Explanation

Enneking Stage IIA represents a high-grade tumor (II) that remains completely intracompartmental (A) without metastases. If it had broken through the cortex into the surrounding soft tissues, it would be classified as Stage IIB.

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