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10. Pathology and Oncology MCQs

Practice Set 68 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 1341

Topic: 10. Pathology and Oncology

The natural history of untreated diffuse Tenosynovial Giant Cell Tumor (TGCT) is progressive joint destruction. The hyperplastic synovium acts as a space-occupying lesion and degrades articular cartilage. Given this, what is the primary goal of surgical management for diffuse TGCT of the knee?

. To achieve joint fusion (arthrodesis) to eliminate pain
. To perform a diagnostic biopsy and then observe for spontaneous regression
. To achieve complete eradication of the abnormal synovial tissue
. To replace the affected joint with a prosthetic implant
. To decompress the joint capsule to relieve effusion

Correct Answer & Explanation

. To achieve complete eradication of the abnormal synovial tissue

Explanation

Correct Answer: C - To achieve complete eradication of the abnormal synovial tissueThe case explicitly states: "The primary goal of treatment is the complete eradication of the abnormal synovial tissue to relieve symptoms, halt joint destruction, and prevent recurrence." This is the fundamental principle behind synovectomy for PVNS.A. To achieve joint fusion (arthrodesis) to eliminate pain:Arthrodesis is a salvage procedure for end-stage arthritis or severe joint destruction, not the primary goal for PVNS, especially in a young patient with preserved joint space.B. To perform a diagnostic biopsy and then observe for spontaneous regression:PVNS does not spontaneously regress. While a biopsy may be performed for diagnostic ambiguity, observation is not a viable definitive strategy for diffuse TGCT due to its progressive nature.D. To replace the affected joint with a prosthetic implant:Total joint arthroplasty may be necessary in cases of severe, end-stage joint destruction secondary to PVNS, but it is not the primary goal of initial surgical management, which aims to preserve the native joint.E. To decompress the joint capsule to relieve effusion:While effusion relief is a temporary benefit, simply decompressing the capsule does not address the underlying proliferative synovial tissue, which is the source of the problem and will lead to recurrence of effusion and continued joint destruction.

Question 1342

Topic: 10. Pathology and Oncology

A 38-year-old male with diffuse Tenosynovial Giant Cell Tumor (TGCT) of the knee, as described in the case, opts against surgical intervention due to personal reasons. If left untreated, what is the most likely long-term outcome for this patient's knee joint?

. Spontaneous regression of the synovial proliferation and resolution of symptoms.
. Development of a malignant transformation into synovial sarcoma.
. Progressive joint destruction leading to severe secondary osteoarthritis, often requiring total joint arthroplasty.
. Chronic, stable effusion with minimal impact on joint function.
. Resolution of mechanical symptoms but persistence of pain and swelling.

Correct Answer & Explanation

. Progressive joint destruction leading to severe secondary osteoarthritis, often requiring total joint arthroplasty.

Explanation

Correct Answer: C - Progressive joint destruction leading to severe secondary osteoarthritis, often requiring total joint arthroplasty.The case explicitly states the natural history of untreated diffuse TGCT: "The natural history of untreated diffuse TGCT is progressive joint destruction. The hyperplastic synovium acts as a space-occupying lesion, causing mechanical damage, while the biochemical environment (metalloproteinases and inflammatory cytokines) degrades articular cartilage. The subchondral erosions eventually lead to structural collapse and severe secondary osteoarthritis, often necessitating premature total joint arthroplasty in young patients."A. Spontaneous regression of the synovial proliferation and resolution of symptoms:PVNS is a locally aggressive, tumor-like condition that does not spontaneously regress.B. Development of a malignant transformation into synovial sarcoma:While PVNS is a tumor-like condition, malignant transformation into synovial sarcoma is exceedingly rare and not considered the typical natural history.D. Chronic, stable effusion with minimal impact on joint function:The disease is progressive, leading to increasing pain, mechanical symptoms, and functional limitations, not a stable state.E. Resolution of mechanical symptoms but persistence of pain and swelling:Mechanical symptoms (catching, giving way, mechanical block) are a prominent feature of PVNS due to the space-occupying nature of the synovium and would worsen, not resolve, without treatment.

Question 1343

Topic: Soft Tissue Tumors & Metastasis

A 35-year-old female presents with recurrent, spontaneous hemorrhagic effusions of her right knee. MRI reveals nodular synovial thickening with low signal intensity on both T1- and T2-weighted images, along with significant "blooming" artifact on gradient-echo sequences. What is the most likely diagnosis?

. Synovial chondromatosis
. Hemophilia A
. Pigmented villonodular synovitis (PVNS)
. Rheumatoid arthritis
. Lipoma arborescens

Correct Answer & Explanation

. Pigmented villonodular synovitis (PVNS)

Explanation

PVNS is characterized by hemosiderin deposition within the synovium, which causes low signal on T1/T2 and a characteristic "blooming" artifact on gradient-echo (T2*) MRI. Spontaneous hemarthrosis in a young adult is a hallmark clinical presentation.

Question 1344

Topic: 10. Pathology and Oncology

A biopsy of hypertrophic synovium from a knee with recurrent atraumatic effusions reveals mononuclear stromal cells, multinucleated giant cells, and hemosiderin-laden macrophages. Which of the following genetic translocations is established in the pathogenesis of this condition?

. t(11;22)
. t(X;18)
. t(1;2) involving the CSF1 gene
. t(12;16)
. t(2;13)

Correct Answer & Explanation

. t(1;2) involving the CSF1 gene

Explanation

PVNS (Tenosynovial Giant Cell Tumor) is a neoplastic process driven by a t(1;2) translocation that fuses the CSF1 gene to the COL6A3 promoter. This leads to overexpression of CSF1, which recruits CSF1-receptor-expressing macrophages and giant cells.

Question 1345

Topic: 10. Pathology and Oncology

A 30-year-old male is diagnosed with diffuse, severe pigmented villonodular synovitis (PVNS) of the knee that has recurred after multiple open synovectomies. He is deemed a candidate for targeted systemic therapy. Which FDA-approved medication, acting as a CSF1R inhibitor, is indicated for this condition?

. Imatinib
. Denosumab
. Pexidartinib
. Rituximab
. Infliximab

Correct Answer & Explanation

. Pexidartinib

Explanation

Pexidartinib is an orally administered colony-stimulating factor 1 receptor (CSF1R) inhibitor. It is the first FDA-approved systemic therapy for symptomatic tenosynovial giant cell tumor (PVNS) associated with severe morbidity or functional limitations not amenable to improvement with surgery.

Question 1346

Topic: 10. Pathology and Oncology

Tenosynovial Giant Cell Tumor (diffuse type, historically known as PVNS) most frequently affects which of the following anatomic locations?

. Shoulder joint
. Hip joint
. Knee joint
. Ankle joint
. Elbow joint

Correct Answer & Explanation

. Knee joint

Explanation

The knee is the most commonly affected joint by both diffuse PVNS and localized nodular tenosynovitis (when inside a large joint). It presents with swelling, pain, locking, and characteristic "chocolate-brown" hemorrhagic effusions.

Question 1347

Topic: 10. Pathology and Oncology

A 35-year-old female presents with chronic knee swelling and pain. MRI reveals a nodular synovial mass with low signal intensity on T1 and T2-weighted sequences, displaying blooming artifact on gradient-echo images. Biopsy is performed. Which of the following histologic findings is characteristic of this condition?

. Mononuclear cells with multinucleated giant cells and hemosiderin deposition
. Chondroid matrix with 'popcorn' calcification
. Spindle cells arranged in a herringbone pattern
. Sheets of uniform small round blue cells with CD99 positivity
. Synovial lining hyperplasia with dense neutrophilic infiltrates

Correct Answer & Explanation

. Mononuclear cells with multinucleated giant cells and hemosiderin deposition

Explanation

The clinical and MRI findings are classic for Pigmented Villonodular Synovitis (PVNS), now more accurately termed Tenosynovial Giant Cell Tumor (TGCT). Histology typically shows lipid-laden macrophages, multinucleated giant cells, and extensive hemosiderin deposition.

Question 1348

Topic: 10. Pathology and Oncology

A 29-year-old male has recurrent, diffuse Pigmented Villonodular Synovitis (PVNS) of the knee despite multiple arthroscopic synovectomies. His oncologist recommends targeted systemic therapy. Which of the following pathways is the primary target of this pharmacologic treatment?

. Vascular Endothelial Growth Factor (VEGF)
. Tumor Necrosis Factor alpha (TNF-a)
. Colony Stimulating Factor 1 Receptor (CSF1R)
. Human Epidermal Growth Factor Receptor 2 (HER2)
. Fibroblast Growth Factor Receptor (FGFR)

Correct Answer & Explanation

. Colony Stimulating Factor 1 Receptor (CSF1R)

Explanation

PVNS (TGCT) is driven by an overexpression of colony-stimulating factor 1 (CSF1) due to a specific chromosomal translocation. Targeted therapies like Pexidartinib (a CSF1R inhibitor) have shown efficacy in treating refractory, diffuse disease.

Question 1349

Topic: 10. Pathology and Oncology

The pathogenesis of localized and diffuse tenosynovial giant cell tumor (formerly PVNS) is most strongly associated with which of the following cytogenetic abnormalities?

. t(11;22)(q24;q12)
. t(X;18)(p11;q11)
. t(12;16)(q13;p11)
. t(1;2)(p13;q37) causing CSF1 overexpression
. t(2;13)(q35;q14)

Correct Answer & Explanation

. t(1;2)(p13;q37) causing CSF1 overexpression

Explanation

PVNS (TGCT) is characterized by a t(1;2)(p13;q37) translocation involving the COL6A3 and CSF1 genes, resulting in the overproduction of CSF1. This attracts the macrophages and multinucleated giant cells that form the bulk of the tumor mass.

Question 1350

Topic: 10. Pathology and Oncology

A 50-year-old female undergoes knee arthroscopy for catching and mechanical symptoms. A 2 cm pedunculated yellowish-brown mass is found attached to the infrapatellar fat pad and is completely excised. The rest of the synovium is normal. What is the most likely diagnosis and appropriate follow-up?

. Diffuse PVNS; start CSF1R inhibitors
. Localized nodular synovitis; routine observation as recurrence is rare
. Synovial sarcoma; staging and wide resection
. Synovial chondromatosis; total synovectomy
. Diffuse PVNS; adjuvant intra-articular radiation

Correct Answer & Explanation

. Localized nodular synovitis; routine observation as recurrence is rare

Explanation

The presentation describes localized tenosynovial giant cell tumor (also known as localized PVNS or nodular synovitis). Unlike the diffuse form, the localized form typically presents as a solitary, resectable nodule and has a very low recurrence rate following simple marginal excision.

Question 1351

Topic: 10. Pathology and Oncology

Which of the following genetic alterations is considered the primary molecular driver in the pathogenesis of tenosynovial giant cell tumor (TGCT/PVNS)?

. t(11;22) EWSR1-FLI1 fusion
. t(X;18) SYT-SSX fusion
. t(1;2) resulting in CSF1 upregulation
. MDM2 gene amplification
. BRAF V600E mutation

Correct Answer & Explanation

. t(1;2) resulting in CSF1 upregulation

Explanation

TGCT/PVNS is a neoplastic process driven by a specific translocation, typically t(1;2)(p13;q37), which fuses the COL6A3 promoter to the CSF1 gene. This leads to an overexpression of Colony Stimulating Factor 1 (CSF1), which attracts macrophages expressing the CSF1 receptor to form the bulk of the tumor mass.

Question 1352

Topic: 10. Pathology and Oncology

A 45-year-old patient with recalcitrant diffuse tenosynovial giant cell tumor (TGCT/PVNS) of the knee is deemed unresectable and is started on pexidartinib. Which of the following represents the FDA black box warning associated with this medication?

. Severe idiosyncratic hepatotoxicity
. Atypical subtrochanteric femur fractures
. Progressive multifocal leukoencephalopathy (PML)
. Irreversible retinal toxicity
. Stevens-Johnson syndrome

Correct Answer & Explanation

. Severe idiosyncratic hepatotoxicity

Explanation

Pexidartinib is a CSF1R inhibitor approved for symptomatic, severe TGCT. It carries an FDA black box warning for potentially fatal hepatotoxicity, requiring frequent liver function monitoring during treatment.

Question 1353

Topic: 10. Pathology and Oncology

Histological evaluation of a biopsy specimen taken from an inflamed knee joint reveals a proliferation of mononuclear cells, multi-nucleated giant cells, and numerous foamy macrophages laden with brown pigment. What is the composition of the characteristic brown pigment found in this condition?

. Melanin
. Lipofuscin
. Hemosiderin
. Homogentisic acid
. Calcium pyrophosphate

Correct Answer & Explanation

. Hemosiderin

Explanation

The diagnosis is Pigmented Villonodular Synovitis (PVNS/TGCT). The characteristic brown pigment seen histologically and macroscopically is hemosiderin, resulting from recurrent microhemorrhages within the highly vascular synovial proliferations.

Question 1354

Topic: 10. Pathology and Oncology

Which of the following descriptions best distinguishes localized tenosynovial giant cell tumor (L-TGCT) from diffuse tenosynovial giant cell tumor (D-TGCT/PVNS)?

. L-TGCT predominantly affects large joints like the knee, whereas D-TGCT affects digits.
. L-TGCT has a high recurrence rate (>40%) following marginal excision, unlike D-TGCT.
. L-TGCT is typically a discrete, pedunculated mass often in the hands or feet, with a low recurrence rate.
. L-TGCT is characterized by malignant transformation, while D-TGCT is entirely benign.
. L-TGCT relies on t(X;18) translocations, while D-TGCT relies on t(1;2) translocations.

Correct Answer & Explanation

. L-TGCT is typically a discrete, pedunculated mass often in the hands or feet, with a low recurrence rate.

Explanation

Localized TGCT (formerly giant cell tumor of tendon sheath) usually presents as a well-circumscribed, often pedunculated mass, frequently in the digits, and has a low recurrence rate post-excision. Diffuse TGCT (classic PVNS) affects the entire synovial lining of larger joints (e.g., knee) and has a very high recurrence rate.

Question 1355

Topic: 10. Pathology and Oncology

A patient with refractory diffuse tenosynovial giant cell tumor (PVNS) of the shoulder is prescribed pexidartinib. Which of the following severe adverse effects requires strict monitoring through a Risk Evaluation and Mitigation Strategy (REMS) program?

. Irreversible retinal toxicity
. Fatal hepatotoxicity
. Severe QT prolongation
. Aplastic anemia
. Pulmonary fibrosis

Correct Answer & Explanation

. Fatal hepatotoxicity

Explanation

Pexidartinib is a CSF1R inhibitor approved for symptomatic, severe TGCT/PVNS not amenable to surgery. It carries a Black Box Warning for fatal and severe hepatotoxicity, requiring frequent liver function testing through a REMS program.

Question 1356

Topic: 10. Pathology and Oncology

Which of the following best describes the pathogenesis of tenosynovial giant cell tumor (PVNS)?

. Polyclonal reactive proliferation of fibroblasts secondary to recurrent hemarthrosis
. Neoplastic proliferation of cells overexpressing Colony Stimulating Factor 1 (CSF1)
. Malignant transformation of synoviocytes due to p53 mutation
. Autoimmune destruction of the synovium leading to giant cell formation
. Infection-induced granulomatous reaction triggered by atypical mycobacteria

Correct Answer & Explanation

. Neoplastic proliferation of cells overexpressing Colony Stimulating Factor 1 (CSF1)

Explanation

PVNS/TGCT is a benign neoplasm driven by a specific translocation, typically t(1;2), that leads to the overexpression of CSF1. This overexpression recruits a large secondary population of non-neoplastic inflammatory cells, primarily macrophages, which form the bulk of the tumor.

Question 1357

Topic: 10. Pathology and Oncology

A 45-year-old female is diagnosed with localized tenosynovial giant cell tumor (PVNS) of the shoulder. Plain radiographs are obtained. Which of the following radiographic findings is most characteristic of this disease process?

. Diffuse periarticular osteopenia
. Extrinsic cystic bone erosions with well-defined sclerotic margins
. Central joint space narrowing with marginal osteophytes
. Extensive matrix calcification within the soft tissue mass
. Periosteal reaction resembling an onion-skin pattern

Correct Answer & Explanation

. Extrinsic cystic bone erosions with well-defined sclerotic margins

Explanation

PVNS typically presents on plain radiographs with preserved joint space and normal bone density (distinguishing it from RA or infection), but it can cause extrinsic, cyst-like erosions with well-defined sclerotic margins on both sides of the joint due to pressure from the hypertrophic synovium.

Question 1358

Topic: Bone Tumors
During distraction osteogenesis, if the rate of distraction is too rapid (e.g., >2.0 mm per day), what is the most likely complication affecting the regenerate bone?
. Premature consolidation of the osteotomy site.
. Delayed consolidation or nonunion of the regenerate.
. Excessive periosteal hypertrophy.
. Hypervascularity leading to arteriovenous fistula formation.
. Development of a symptomatic osteochondroma.

Correct Answer & Explanation

. Delayed consolidation or nonunion of the regenerate.

Explanation

The optimal rate for distraction osteogenesis is 1 mm per day. Rates exceeding this frequently lead to poor regenerate formation, delayed consolidation, or nonunion.

Question 1359

Topic: 10. Pathology and Oncology

A 28-year-old aquarium worker presents with a chronic, nodular, and ulcerating lesion on the dorsum of his right hand that appeared 3 weeks after cleaning a fish tank. If a biopsy is sent for culture, which specific laboratory parameter is crucial for isolating the most likely causative organism?

. Anaerobic conditions with high CO2 tension
. Incubation at an optimal temperature of 30°C to 32°C
. Culture on Thayer-Martin agar
. Prolonged incubation strictly at 37°C for 6 weeks
. Use of Sabouraud dextrose agar with cycloheximide

Correct Answer & Explanation

. Incubation at an optimal temperature of 30°C to 32°C

Explanation

Mycobacterium marinum is an atypical mycobacterium associated with fish and marine environments. It requires a cooler incubation temperature of 30°C to 32°C for optimal growth, which corresponds to the temperature of the cooler peripheral extremities where it causes disease.

Question 1360

Topic: 10. Pathology and Oncology

Question 1

A 52-year-old right-hand dominant carpenter presents with a firm, mobile, non-tender mass on the volar aspect of his left wrist, which has been slowly growing over the past year. He reports mild discomfort with repetitive wrist flexion and extension, but no neurological symptoms. Physical examination confirms a 2x1.5 cm mass, distinct from tendons, with no overlying skin changes. Imaging (ultrasound and MRI) suggests a benign soft tissue tumor, likely a lipoma or giant cell tumor of the tendon sheath, with close proximity to the radial artery and superficial branch of the radial nerve. The patient is considering surgical excision due to increasing mechanical interference with his work. Based on the principles outlined in the case, why is a 'wide local excision' (WLE) approach generally considered detrimental for this type of benign hand mass?

. A. WLE significantly increases the risk of malignant transformation of benign lesions.
. B. WLE is associated with a higher rate of recurrence for benign hand masses compared to precise excision.
. C. The compact anatomy of the hand means WLE risks iatrogenic injury to critical neurovascular structures, tendons, and joints, leading to functional deficits.
. D. WLE often results in inadequate margins for hand masses, necessitating re-excision.
. E. WLE is only indicated for cystic lesions, not solid tumors, in the hand.

Correct Answer & Explanation

. C. The compact anatomy of the hand means WLE risks iatrogenic injury to critical neurovascular structures, tendons, and joints, leading to functional deficits.

Explanation

Correct Answer: CThe case explicitly states that 'The compact nature of critical neurovascular structures, tendons, and joint capsules within the hand means that indiscriminate 'wide' margins can lead to significant iatrogenic morbidity, including nerve injury, vascular compromise, tendon rupture, joint stiffness, and profound functional deficits.' For benign hand masses, the objective is precise, en bloc excision with meticulous preservation of adjacent healthy, functional structures, rather than the removal of a broad cuff of uninvolved tissue.Option A is incorrect.There is no evidence that WLE increases the risk of malignant transformation of benign lesions. The concern with WLE in the hand is iatrogenic damage, not oncologic transformation.Option B is incorrect.For benign lesions like GCTTS, recurrence is primarily due to incomplete excision, not the width of the margin of healthy tissue removed. WLE, by damaging surrounding structures, might even complicate subsequent re-excision if recurrence occurs.Option D is incorrect.WLE, by definition, aims for wide margins. The issue in the hand is that these 'wide' margins are often unnecessary for benign lesions and cause more harm than good due to the dense packing of vital structures. For benign lesions, 'tumor-free margins immediately adjacent to the lesion' are sufficient, not wide margins of healthy tissue.Option E is incorrect.The principle against WLE applies to most benign hand masses, whether cystic (e.g., ganglion cysts) or solid (e.g., lipomas, GCTTS). The commonality is their benign nature and the need for functional preservation.

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