Mesothelioma Diagnosis Clinical Knowledge Assessment — Questions and Answers

Question 1: What does an elevated serum CRP (C-reactive protein) indicate in the context of mesothelioma?

Presence of sarcomatoid differentiation
Response to chemotherapy
Benign reactive pleural disease
Active systemic inflammation associated with worse prognosis (Correct answer)

Correct answer: Active systemic inflammation associated with worse prognosis

Elevated CRP reflects tumor-driven systemic inflammation in mesothelioma and is an independent predictor of poor prognosis.

Question 2: Hyaluronan (hyaluronic acid) levels are elevated in pleural fluid of mesothelioma patients. This is because:

It reflects liver dysfunction
Mesothelioma cells produce large amounts of hyaluronan (Correct answer)
Bacteria in the pleural space produce it
Lung cancer metastases secrete it

Correct answer: Mesothelioma cells produce large amounts of hyaluronan

Malignant mesothelial cells actively secrete hyaluronan into pleural fluid, and markedly elevated levels support a mesothelioma diagnosis.

Question 3: Ultrasound of the chest in mesothelioma is most useful for which clinical application?

Lymph node mapping
Full tumor staging
Mediastinal assessment
Guiding thoracentesis and pleural biopsy (Correct answer)

Correct answer: Guiding thoracentesis and pleural biopsy

Ultrasound is primarily used at the bedside to guide thoracentesis (fluid drainage) and image-guided pleural biopsy safely.

Question 4: Which condition most commonly causes benign pleural thickening that mimics mesothelioma on imaging?

Pulmonary sarcoidosis
Spontaneous pneumothorax
Pulmonary embolism
Fibrothorax from prior empyema or hemothorax (Correct answer)

Correct answer: Fibrothorax from prior empyema or hemothorax

Fibrothorax resulting from prior infection, hemorrhage, or trauma causes benign pleural fibrosis that can radiologically resemble malignant pleural disease.

Question 5: Elevated serum SMRP is most specific for which mesothelioma cell type?

Sarcomatoid
Epithelioid (Correct answer)
Desmoplastic
Biphasic

Correct answer: Epithelioid

SMRP is primarily expressed by epithelioid mesothelioma cells; sarcomatoid tumors express little to no mesothelin, reducing biomarker sensitivity in those cases.

Question 6: What finding on chest X-ray is most commonly associated with pleural mesothelioma?

Pulmonary nodules
Mediastinal widening
Pneumothorax
Pleural effusion (Correct answer)

Correct answer: Pleural effusion

Pleural effusion (fluid buildup in the pleural space) is the most common initial radiographic finding in pleural mesothelioma.

Question 7: Which combination of IHC markers is commonly used as a positive panel for epithelioid mesothelioma?

GATA3, ER, PR, GCDFP-15
TTF-1, Napsin A, CEA, MOC-31
CDX2, CK20, villin, CEA
Calretinin, WT1, CK5/6, D2-40 (Correct answer)

Correct answer: Calretinin, WT1, CK5/6, D2-40

Calretinin, WT1, CK5/6, and D2-40 form a standard positive mesothelial IHC panel used to support a diagnosis of epithelioid mesothelioma.

Question 8: What is the significance of finger clubbing in a patient being evaluated for mesothelioma?

It rules out mesothelioma and suggests primary lung cancer instead
It indicates successful response to treatment
It suggests underlying chronic hypoxia and pulmonary disease, raising suspicion for advanced thoracic malignancy (Correct answer)
It is pathognomonic for mesothelioma

Correct answer: It suggests underlying chronic hypoxia and pulmonary disease, raising suspicion for advanced thoracic malignancy

Finger clubbing indicates chronic hypoxia or pulmonary disease and, combined with other findings, raises suspicion for advanced thoracic malignancy including mesothelioma.

Question 9: Serum osteopontin has been proposed as a mesothelioma screening biomarker in asbestos-exposed individuals because:

It is specific for peritoneal disease
It is elevated in asbestos-exposed individuals who develop mesothelioma compared to exposed but disease-free individuals (Correct answer)
It is only elevated after symptoms begin
It replaces imaging in annual surveillance

Correct answer: It is elevated in asbestos-exposed individuals who develop mesothelioma compared to exposed but disease-free individuals

Serum osteopontin is significantly elevated in asbestos-exposed individuals who develop mesothelioma, suggesting a role in surveillance of high-risk populations.

Question 10: Pleural involvement by thymoma (type B3) may mimic biphasic mesothelioma; which FISH finding confirms thymoma?

BAP1 loss
Homozygous CDKN2A deletion
Absence of CDKN2A deletion and presence of chromosome 6 abnormalities (Correct answer)
NF2 deletion

Correct answer: Absence of CDKN2A deletion and presence of chromosome 6 abnormalities

Thymoma does not harbor CDKN2A homozygous deletion (which confirms mesothelioma malignancy) and may show chromosome 6 alterations characteristic of thymic tumors.

Question 11: What does T4 disease represent in the IMIG staging of pleural mesothelioma?

Involvement of the pericardium without cardiac invasion
Invasion of the diaphragm only
Direct extension into contralateral pleura, spine, or heart (Correct answer)
Ipsilateral pleural disease with effusion

Correct answer: Direct extension into contralateral pleura, spine, or heart

T4 denotes extension beyond local structures to involve the contralateral pleura, peritoneum, spine, heart, or brachial plexus — all indicating unresectable disease.

Question 12: PET scan (FDG-PET) is used in mesothelioma primarily for which purpose?

Measuring pleural fluid volume
Guiding needle biopsy
Detecting distant metastases and nodal involvement (Correct answer)
Assessing lung function

Correct answer: Detecting distant metastases and nodal involvement

FDG-PET imaging is used in mesothelioma to detect distant metastatic disease and mediastinal lymph node involvement to guide staging.

Question 13: Which characteristic morphological feature differentiates epithelioid mesothelioma from reactive mesothelial hyperplasia on histology?

Cell size
Mitotic rate alone
Stromal invasion (Correct answer)
Nuclear pleomorphism alone

Correct answer: Stromal invasion

Stromal invasion is the definitive histological feature of malignancy; reactive mesothelial cells may appear atypical but do not invade underlying stroma.

Question 14: Pleural epithelioid hemangioendothelioma (EHE) is distinguished from mesothelioma by positive staining for which marker?

D2-40
CD31 and ERG (endothelial markers) (Correct answer)
WT1
Calretinin

Correct answer: CD31 and ERG (endothelial markers)

EHE is a vascular tumor that stains for endothelial markers CD31 and ERG, which are absent in mesothelioma.

Question 15: Which malignancy most commonly mimics pleural mesothelioma on imaging and requires IHC for differentiation?

Primary pleural lymphoma
Metastatic lung adenocarcinoma (Correct answer)
Pulmonary carcinoid
Primary lung squamous cell carcinoma

Correct answer: Metastatic lung adenocarcinoma

Metastatic lung adenocarcinoma to the pleura can produce diffuse pleural thickening identical to mesothelioma on imaging, requiring IHC to differentiate.

Question 16: Which complete blood count (CBC) finding is associated with advanced mesothelioma and poor prognosis?

Neutropenia
Lymphocytosis
Thrombocytosis (Correct answer)
Eosinophilia

Correct answer: Thrombocytosis

Paraneoplastic thrombocytosis (elevated platelet count) is common in advanced mesothelioma and is associated with poor survival outcomes.

Question 17: Which staging system is most widely used for malignant pleural mesothelioma in the US?

FIGO staging
IMIG/IASLC TNM staging system (Correct answer)
Dukes staging
Ann Arbor classification

Correct answer: IMIG/IASLC TNM staging system

The IMIG/IASLC TNM-based staging system is the standard for malignant pleural mesothelioma, incorporated into the AJCC Cancer Staging Manual.

Question 18: Pleural plaques seen on CT are important in mesothelioma diagnosis because they indicate:

Current active tumor
Autoimmune pleuritis
Bacterial infection
Prior asbestos exposure (Correct answer)

Correct answer: Prior asbestos exposure

Calcified pleural plaques are a marker of prior asbestos exposure and, while benign themselves, raise suspicion for asbestos-related malignancy.

Question 19: Which cell type in mesothelioma is associated with the best prognosis?

Biphasic
Epithelioid (Correct answer)
Sarcomatoid
Desmoplastic

Correct answer: Epithelioid

Epithelioid mesothelioma cells are well-defined and respond better to treatment, giving patients the best prognosis.

Question 20: In sarcomatoid mesothelioma, which IHC marker is most reliably positive?

D2-40
WT1
Pancytokeratin (Correct answer)
Calretinin

Correct answer: Pancytokeratin

Pancytokeratin (AE1/AE3) staining is the most consistently positive marker in sarcomatoid mesothelioma, as calretinin and WT1 are often lost in this subtype.

Question 21: Which laboratory finding in pleural fluid analysis is characteristic of a malignant exudative effusion?

Normal LDH and low pH
Low glucose and high amylase
Low LDH and low protein
High LDH and high protein (Correct answer)

Correct answer: High LDH and high protein

Malignant pleural effusions are exudates characterized by high LDH (>200 IU/L) and high protein (>3 g/dL) using Light's criteria.

Question 22: Tuberculous pleuritis causing pleural thickening can mimic mesothelioma; how is it best differentiated?

Elevated pleural LDH alone
CT showing circumferential thickening
Microbiological culture, AFB staining, and ADA levels in pleural fluid (Correct answer)
Serum SMRP elevation

Correct answer: Microbiological culture, AFB staining, and ADA levels in pleural fluid

TB pleuritis is confirmed by AFB staining, mycobacterial culture, and markedly elevated adenosine deaminase (ADA) in pleural fluid, which are absent in mesothelioma.

Question 23: PD-L1 expression measured by IHC in mesothelioma tissue is clinically relevant because:

It confirms the diagnosis of mesothelioma
It may predict response to immune checkpoint inhibitor therapy (Correct answer)
It is used to calculate staging
It indicates sarcomatoid cell type

Correct answer: It may predict response to immune checkpoint inhibitor therapy

PD-L1 expression levels guide decisions about immunotherapy with checkpoint inhibitors such as pembrolizumab or nivolumab in mesothelioma patients.

Question 24: A patient with peritoneal mesothelioma is most likely to present with which of the following?

Hematuria and flank pain
Jaundice and hepatomegaly
Abdominal distension and ascites (Correct answer)
Hemoptysis and pleurisy

Correct answer: Abdominal distension and ascites

Peritoneal mesothelioma typically presents with abdominal distension due to malignant ascites and diffuse peritoneal involvement.

Question 25: In peritoneal mesothelioma, which CT feature best predicts completeness of cytoreductive surgery?

Peritoneal cancer index (PCI) score (Correct answer)
Tumor size at a single location
Presence of liver metastases
Ascites volume

Correct answer: Peritoneal cancer index (PCI) score

A low PCI score on preoperative CT predicts that complete cytoreduction is achievable, which is the strongest predictor of long-term survival.

Question 26: What is the advantage of using integrated PET/CT over CT alone in staging mesothelioma?

Higher spatial resolution for pleural detail
Better assessment of fluid density
Better detection of occult nodal and distant metastatic disease (Correct answer)
Lower radiation dose

Correct answer: Better detection of occult nodal and distant metastatic disease

PET/CT combines functional metabolic data with anatomical detail, improving detection of nodal metastases and distant spread that CT alone may miss.

Question 27: Which gender is more commonly diagnosed with mesothelioma in the US?

Men (Correct answer)
Both equally
Women
Depends on the subtype

Correct answer: Men

Men are diagnosed with mesothelioma far more often than women due to historical occupational asbestos exposure in male-dominated industries.

Question 28: Which CT finding helps differentiate malignant pleural mesothelioma from a benign pleural effusion?

Absence of contrast enhancement
Simple fluid density without loculation
Bilateral symmetric pleural involvement
Pleural nodularity and thickening >1 cm (Correct answer)

Correct answer: Pleural nodularity and thickening >1 cm

Pleural nodularity and pleural thickening greater than 1 cm are CT features that strongly suggest malignancy rather than benign effusion.

Question 29: Which factor is the single most important determinant of survival in mesothelioma?

Side of involvement (left vs. right)
Pleural effusion volume
Age at diagnosis
Histological cell type (epithelioid vs. sarcomatoid) (Correct answer)

Correct answer: Histological cell type (epithelioid vs. sarcomatoid)

Epithelioid cell type confers significantly better median survival than sarcomatoid or biphasic types, making histology the strongest prognostic variable.

Question 30: What is the minimum tissue requirement for a definitive mesothelioma diagnosis according to current guidelines?

Cytology from thoracentesis alone
Core biopsy with sufficient tissue for IHC (Correct answer)
Imaging findings without biopsy
Fine needle aspirate only

Correct answer: Core biopsy with sufficient tissue for IHC

Current guidelines require a core biopsy with adequate tissue for histological assessment and immunohistochemical panel to confirm mesothelioma.

Question 31: Which radiologic sign on chest X-ray suggests mesothelioma has encased and contracted the affected hemithorax?

Apical pleural capping
Bilateral pleural effusions
Contralateral mediastinal shift
Ipsilateral volume loss with pleural thickening (Correct answer)

Correct answer: Ipsilateral volume loss with pleural thickening

Mesothelioma often causes ipsilateral volume loss because the tumor encases and constricts the lung, rather than pushing the mediastinum to the opposite side.

Question 32: TTF-1 (thyroid transcription factor-1) positivity in a pleural biopsy would support a diagnosis of:

Epithelioid mesothelioma
Sarcomatoid mesothelioma
Metastatic lung adenocarcinoma (Correct answer)
Pleural fibroma

Correct answer: Metastatic lung adenocarcinoma

TTF-1 is a marker of lung and thyroid epithelial origin; its positivity in pleural disease supports metastatic lung adenocarcinoma rather than mesothelioma.

Question 33: What is the role of next-generation sequencing (NGS) in mesothelioma diagnosis?

Identifying actionable mutations and confirming malignancy (Correct answer)
Measuring mesothelin expression
Assessing asbestos burden in tissue
Replacing IHC for routine diagnosis

Correct answer: Identifying actionable mutations and confirming malignancy

NGS identifies somatic mutations (e.g., BAP1, NF2, CDKN2A) that confirm malignancy and may reveal targetable alterations for clinical trials.

Question 34: Paraganglioma occurring in the posterior mediastinum may mimic mesothelioma on imaging; it is distinguished by positive staining for:

TTF-1 and Napsin A
CK5/6 and D2-40
Calretinin and WT1
Synaptophysin and chromogranin A (Correct answer)

Correct answer: Synaptophysin and chromogranin A

Paragangliomas are neuroendocrine tumors that express synaptophysin and chromogranin A, neuroendocrine markers completely absent in mesothelioma.

Question 35: Which biomarker found in pleural fluid is used to differentiate malignant from benign pleural effusions?

Lactate dehydrogenase (LDH)
pH
Mesothelin (Correct answer)
Glucose

Correct answer: Mesothelin

Elevated mesothelin levels in pleural fluid support a malignant mesothelioma diagnosis and help distinguish it from benign causes of effusion.

Question 36: MicroRNA-625-3p in pleural effusion has been studied as a mesothelioma biomarker because:

It predicts surgical margins
It measures asbestos-induced DNA damage
It is elevated in malignant effusions and may improve cytological diagnosis (Correct answer)
It indicates BAP1 loss

Correct answer: It is elevated in malignant effusions and may improve cytological diagnosis

MicroRNA-625-3p levels are elevated in pleural fluid from mesothelioma patients and may augment cytological diagnosis in indeterminate cases.

Question 37: Cytological analysis of pleural fluid in mesothelioma has which major limitation?

Cannot detect malignant cells
Low sensitivity and inability to subtype the tumor (Correct answer)
Always yields insufficient sample
High false-positive rate

Correct answer: Low sensitivity and inability to subtype the tumor

Pleural fluid cytology has low sensitivity (around 32%) for mesothelioma and cannot reliably subtype the tumor, making tissue biopsy necessary.

Question 38: Which IHC marker is characteristically positive in epithelioid mesothelioma?

CEA
Napsin A
Calretinin (Correct answer)
TTF-1

Correct answer: Calretinin

Calretinin is a highly sensitive and specific positive marker for mesothelioma and is routinely included in diagnostic IHC panels.

Question 39: Which type of chest pain is most characteristically associated with pleural mesothelioma?

Dull, persistent, non-pleuritic chest pain (Correct answer)
Sharp pleuritic pain that worsens with deep inspiration
Central crushing chest pain
Intermittent anginal pain relieved by rest

Correct answer: Dull, persistent, non-pleuritic chest pain

Pleural mesothelioma typically causes a dull, persistent, non-pleuritic chest pain due to direct tumor involvement of the chest wall and parietal pleura.

Question 40: Which imaging finding on CT is used to calculate the peritoneal cancer index (PCI) in peritoneal mesothelioma?

Volume of ascites
Diameter of the largest lymph node
Distribution and size of peritoneal tumor deposits (Correct answer)
Thickness of the bowel wall

Correct answer: Distribution and size of peritoneal tumor deposits

The PCI is calculated by scoring the size and distribution of tumor deposits across 13 abdominal regions on CT to guide surgical planning.

Question 41: Which nuclear medicine finding on PET scan is associated with higher-grade or sarcomatoid mesothelioma?

Absent FDG uptake
Low SUV
High SUV (standardized uptake value) (Correct answer)
Uniform low-level uptake

Correct answer: High SUV (standardized uptake value)

High FDG uptake (high SUV) on PET correlates with more aggressive tumor biology, including sarcomatoid differentiation and worse prognosis.

Question 42: Which prognostic scoring system for mesothelioma uses lactate dehydrogenase, age, performance status, and hemoglobin?

Brigham staging
CALGB prognostic score (Correct answer)
IMIG TNM
EORTC score

Correct answer: CALGB prognostic score

The CALGB (Cancer and Leukemia Group B) prognostic score uses LDH, age, performance status, and hemoglobin to classify patients into good, intermediate, and poor risk groups.

Question 43: The combination of nivolumab and ipilimumab has been approved for first-line treatment of mesothelioma based on which trial?

EMPHACIS
KEYNOTE-158
CheckMate 743 (Correct answer)
MAPS2

Correct answer: CheckMate 743

The CheckMate 743 trial demonstrated improved overall survival with nivolumab plus ipilimumab versus chemotherapy, leading to FDA approval for first-line mesothelioma.

Question 44: Which IHC profile helps distinguish pleural mesothelioma (positive) from metastatic adenocarcinoma (negative)?

CEA positive, WT1 negative
Calretinin positive, CEA negative (Correct answer)
TTF-1 positive, calretinin negative
MOC-31 positive, D2-40 negative

Correct answer: Calretinin positive, CEA negative

Mesothelioma characteristically stains positive for calretinin and negative for CEA, while the reverse pattern is seen in metastatic adenocarcinoma.

Question 45: What is the primary cause of all types of mesothelioma?

Asbestos exposure (Correct answer)
Genetic mutation
Radiation exposure
Smoking

Correct answer: Asbestos exposure

Asbestos exposure is the primary known cause of mesothelioma, responsible for the vast majority of cases across all anatomical types.

Question 46: Loss of BRCA1-associated protein 1 (BAP1) expression on IHC is significant in mesothelioma because:

It confirms malignancy and distinguishes from reactive mesothelial proliferation (Correct answer)
It rules out sarcomatoid differentiation
It indicates favorable prognosis
It is present in all benign pleural disease

Correct answer: It confirms malignancy and distinguishes from reactive mesothelial proliferation

Loss of BAP1 nuclear expression strongly supports malignant mesothelioma and helps distinguish it from benign reactive mesothelial hyperplasia.

Question 47: Which stain is used on routine pathology sections to first evaluate suspected mesothelioma?

Hematoxylin and eosin (H&E) (Correct answer)
Masson trichrome
Sudan black
PAS stain

Correct answer: Hematoxylin and eosin (H&E)

H&E staining is the standard first-line histological stain used to assess tumor morphology and cell type in all biopsy specimens.

Question 48: On CT imaging, which feature is most suggestive of peritoneal mesothelioma?

Retroperitoneal lymphadenopathy alone
Diffuse peritoneal thickening with ascites (Correct answer)
Single large abdominal mass
Isolated hepatic lesion

Correct answer: Diffuse peritoneal thickening with ascites

Peritoneal mesothelioma typically appears on CT as diffuse peritoneal thickening or nodularity accompanied by ascites.

Question 49: What is the significance of the NF2 gene mutation in mesothelioma pathology?

It indicates asbestos-free etiology
It is one of the most common somatic mutations found in mesothelioma (Correct answer)
It predicts response to immunotherapy
It is found only in pericardial mesothelioma

Correct answer: It is one of the most common somatic mutations found in mesothelioma

NF2 (merlin) mutation is among the most frequently identified somatic mutations in malignant mesothelioma, found in approximately 40% of tumors.

Question 50: Solitary fibrous tumor of the pleura (SFTP) is distinguished from mesothelioma by which key feature?

It is usually localized and has a pedunculated attachment to the pleura (Correct answer)
It is diffuse and bilateral
It always occurs in asbestos-exposed workers
It is always malignant

Correct answer: It is usually localized and has a pedunculated attachment to the pleura

SFTP is typically a well-circumscribed, pedunculated, localized mass attached to the pleura by a stalk, in contrast to the diffuse pleural involvement of mesothelioma.

Question 51: In the IMIG TNM staging system, Stage I mesothelioma is characterized by:

Tumor confined to the ipsilateral pleura without nodal involvement (Correct answer)
Distant metastases present
Ipsilateral mediastinal lymph node involvement
Contralateral pleural involvement

Correct answer: Tumor confined to the ipsilateral pleura without nodal involvement

Stage I (IA and IB) mesothelioma is limited to the ipsilateral pleura with no lymph node involvement or distant spread.

Question 52: The EORTC prognostic score for mesothelioma assigns worse prognosis to which patient profile?

Age under 50 with epithelioid type
Low LDH and no weight loss
Non-epithelioid histology, poor performance status, and high WBC (Correct answer)
Female gender and early stage

Correct answer: Non-epithelioid histology, poor performance status, and high WBC

The EORTC score identifies poor-prognosis patients based on non-epithelioid histology, poor ECOG performance status, elevated WBC, and other factors.

Question 53: Which procedure is considered the gold standard for diagnosing malignant pleural mesothelioma?

CT-guided FNA
Video-assisted thoracoscopic surgery (VATS) biopsy (Correct answer)
Bronchoscopy
Thoracentesis alone

Correct answer: Video-assisted thoracoscopic surgery (VATS) biopsy

VATS biopsy provides large tissue samples under direct visualization and is the gold standard for diagnosing and staging pleural mesothelioma.

Question 54: What is the clinical utility of serum SMRP levels in mesothelioma?

Definitive diagnosis without biopsy
Monitoring disease progression and treatment response (Correct answer)
Predicting surgical candidacy
Identifying asbestos fiber type

Correct answer: Monitoring disease progression and treatment response

SMRP levels correlate with tumor burden and can be used to monitor disease progression and response to treatment, though they cannot replace biopsy for diagnosis.

Question 55: What percentage of all mesothelioma cases does pleural mesothelioma account for?

About 25%
About 50%
About 75% (Correct answer)
About 90%

Correct answer: About 75%

Pleural mesothelioma accounts for approximately 75% of all diagnosed mesothelioma cases in the US.

Question 56: Median overall survival for malignant pleural mesothelioma treated with standard chemotherapy is approximately:

30–36 months
12–18 months (Correct answer)
5 years
3–6 months

Correct answer: 12–18 months

With first-line cisplatin/pemetrexed chemotherapy, median overall survival is approximately 12 to 18 months from diagnosis.

Question 57: Immunohistochemistry (IHC) is essential in mesothelioma pathology primarily to:

Assess vascular invasion
Distinguish mesothelioma from adenocarcinoma (Correct answer)
Determine asbestos fiber burden
Measure tumor size

Correct answer: Distinguish mesothelioma from adenocarcinoma

IHC panels are used to differentiate mesothelioma from metastatic adenocarcinoma, which can be morphologically identical on routine staining.

Question 58: What is the typical latency period between asbestos exposure and the clinical presentation of mesothelioma?

Over 60 years
1–5 years
5–10 years
20–50 years (Correct answer)

Correct answer: 20–50 years

Mesothelioma has a latency period of 20–50 years between initial asbestos exposure and clinical presentation, which is why patients are often elderly at diagnosis.

Question 59: In mesothelioma imaging, contralateral pleural disease or pericardial extension indicates which TNM stage?

Stage III
Stage IV (Correct answer)
Stage I
Stage II

Correct answer: Stage IV

Extension to contralateral pleura or pericardium indicates advanced T4 disease, placing the patient in Stage IV of the IMIG staging system.

Question 60: Which imaging finding would most likely prompt a change from surgical to palliative management in pleural mesothelioma?

Mediastinal lymph node involvement on PET/CT (Correct answer)
Single pleural nodule without invasion
Small ipsilateral pleural effusion
Pleural thickening less than 5 mm

Correct answer: Mediastinal lymph node involvement on PET/CT

Mediastinal nodal involvement (N2 disease) indicates unresectable disease in most staging systems, often redirecting management toward palliative intent.

Question 61: D2-40 (podoplanin) IHC staining in mesothelioma primarily highlights which feature?

Mitotic figures
Lymphatic differentiation and mesothelial cells (Correct answer)
Vascular endothelium
Necrosis zones

Correct answer: Lymphatic differentiation and mesothelial cells

D2-40 stains lymphatic endothelium and mesothelial cells, and its expression supports a mesothelial origin in pleural biopsies.

Question 62: Serum SMRP testing has FDA approval as an aid for which clinical purpose in mesothelioma?

Screening the general population
Monitoring previously diagnosed mesothelioma patients (Correct answer)
Primary diagnosis without biopsy
Predicting surgical outcomes

Correct answer: Monitoring previously diagnosed mesothelioma patients

The FDA approved SMRP (Mesomark assay) as an aid for monitoring patients with epithelioid or biphasic mesothelioma, not for primary diagnosis or screening.

Question 63: Primary pleural thymoma is distinguished from mesothelioma by positive expression of which marker?

CEA and MOC-31
Calretinin and WT1
CD5 and PAX8 in epithelial thymoma cells (Correct answer)
D2-40 and CK5/6 alone

Correct answer: CD5 and PAX8 in epithelial thymoma cells

Ectopic thymoma in the pleural cavity expresses CD5 and PAX8 in its epithelial component, markers absent in mesothelioma.

Question 64: FISH (fluorescence in situ hybridization) for CDKN2A (p16) deletion is used in mesothelioma pathology to:

Assess treatment response
Distinguish malignant mesothelioma from benign mesothelial hyperplasia (Correct answer)
Determine asbestos fiber type
Grade tumor differentiation

Correct answer: Distinguish malignant mesothelioma from benign mesothelial hyperplasia

Homozygous deletion of CDKN2A detected by FISH is a reliable molecular marker of malignancy in mesothelioma, distinguishing it from benign reactive proliferations.

Question 65: A pleural biopsy showing diffuse large B-cell lymphoma cells would be differentiated from mesothelioma by which finding?

BAP1 loss
CD20 positivity and cytokeratin negativity (Correct answer)
Calretinin positivity
CDKN2A deletion

Correct answer: CD20 positivity and cytokeratin negativity

DLBCL expresses B-cell marker CD20 and lacks cytokeratin expression, which is the opposite of mesothelioma's keratin-positive, CD20-negative profile.

Question 66: Which imaging study is most useful for assessing the extent of chest wall invasion in mesothelioma?

MRI (Correct answer)
Ultrasound
PET scan
Chest X-ray

Correct answer: MRI

MRI provides superior soft tissue contrast and is the best modality for evaluating chest wall, diaphragm, and mediastinal invasion in mesothelioma staging.

Question 67: Fibulin-3 as a mesothelioma biomarker is measured in which biological fluid?

Plasma and pleural fluid (Correct answer)
Cerebrospinal fluid
Sputum
Urine only

Correct answer: Plasma and pleural fluid

Fibulin-3 levels can be measured in both plasma and pleural fluid and have shown promise as a mesothelioma diagnostic and prognostic biomarker.

Question 68: Which performance status scale is most commonly used to assess mesothelioma patients' fitness for treatment?

WHO disability grade
ECOG performance status (Correct answer)
NYHA functional class
Karnofsky score only

Correct answer: ECOG performance status

ECOG (Eastern Cooperative Oncology Group) performance status 0–2 is the standard measure used in clinical trials and treatment decisions for mesothelioma.

Question 69: Which of the following best explains why mesothelioma is frequently misdiagnosed at initial presentation?

CT imaging is 100% specific for the diagnosis
Blood tests reliably confirm mesothelioma in early stages
Early symptoms mimic common benign conditions like pleuritis or pneumonia (Correct answer)
It always presents with pathognomonic symptoms unique to mesothelioma

Correct answer: Early symptoms mimic common benign conditions like pleuritis or pneumonia

Early mesothelioma symptoms such as dyspnea and chest pain are non-specific and can mimic benign conditions, leading to significant diagnostic delays.

Question 70: Sarcomatoid mesothelioma is characterized by which of the following?

Mixed cell types and moderate prognosis
Spindle-shaped cells and poor prognosis (Correct answer)
Glandular structures and variable prognosis
Round epithelial cells and good prognosis

Correct answer: Spindle-shaped cells and poor prognosis

Sarcomatoid mesothelioma consists of spindle-shaped cells and is the most aggressive cell type with the worst prognosis.

Question 71: Pleural involvement by breast carcinoma can be excluded in favor of mesothelioma by the absence of which markers?

D2-40 and CK5/6
TTF-1 and Napsin A
Calretinin and WT1
ER, GATA3, and mammaglobin (Correct answer)

Correct answer: ER, GATA3, and mammaglobin

ER, GATA3, and mammaglobin are breast carcinoma markers; their absence, combined with positive mesothelial markers, supports mesothelioma over metastatic breast cancer.

Question 72: Localized malignant mesothelioma is distinguished from diffuse malignant mesothelioma primarily by:

Requirement for HIPEC treatment
Cell type — always sarcomatoid
Earlier lymph node involvement
Its discrete, localized mass without diffuse pleural spread (Correct answer)

Correct answer: Its discrete, localized mass without diffuse pleural spread

Localized malignant mesothelioma presents as a distinct mass without the diffuse pleural coating typical of diffuse mesothelioma, and is potentially curable with surgery.

Question 73: Which type of mesothelioma develops in the lining of the abdomen?

Pericardial mesothelioma
Peritoneal mesothelioma (Correct answer)
Testicular mesothelioma
Pleural mesothelioma

Correct answer: Peritoneal mesothelioma

Peritoneal mesothelioma originates in the peritoneum, the membrane that lines the abdominal cavity.

Question 74: CT scan of the chest in pleural mesothelioma most characteristically shows which finding?

Bilateral hilar adenopathy
Central lung mass
Circumferential pleural thickening (Correct answer)
Ground-glass opacities

Correct answer: Circumferential pleural thickening

CT imaging typically reveals circumferential or nodular pleural thickening, often encasing the lung, which is highly characteristic of malignant pleural mesothelioma.

Question 75: The desmoplastic subtype is a variant of which mesothelioma cell type?

Sarcomatoid (Correct answer)
Biphasic
Epithelioid
Peritoneal

Correct answer: Sarcomatoid

Desmoplastic mesothelioma is a rare, aggressive subtype of sarcomatoid mesothelioma characterized by dense fibrous stroma.

Question 76: Electron microscopy in mesothelioma diagnosis is used to identify which ultrastructural feature?

Long, slender microvilli on tumor cell surface (Correct answer)
Weibel-Palade bodies
Desmosomes only
Mucin granules

Correct answer: Long, slender microvilli on tumor cell surface

Mesothelioma cells characteristically show long, slender microvilli on electron microscopy, in contrast to the short, stubby microvilli of adenocarcinoma.

Question 77: Peritoneal mesothelioma must be differentiated from primary peritoneal carcinoma by which IHC finding?

Calretinin and WT1 positive vs. PAX8 and ER positive in carcinoma (Correct answer)
CEA positivity in mesothelioma
TTF-1 in mesothelioma
CK20 in mesothelioma vs. CK7 in carcinoma

Correct answer: Calretinin and WT1 positive vs. PAX8 and ER positive in carcinoma

Peritoneal mesothelioma stains positive for calretinin and WT1 while primary peritoneal serous carcinoma stains positive for PAX8, ER, and Ber-EP4.

Question 78: Which physical examination finding is most commonly detected in pleural mesothelioma?

Tracheal deviation toward the affected side
Hyperresonance to percussion on the affected side
Dullness to percussion with decreased breath sounds on the affected side (Correct answer)
Bilateral crackles on auscultation

Correct answer: Dullness to percussion with decreased breath sounds on the affected side

Pleural effusion, the hallmark finding in pleural mesothelioma, produces dullness to percussion and decreased breath sounds on the affected side.

Question 79: Which finding would most strongly suggest mesothelioma over benign asbestos-related pleural disease on CT?

Bilateral calcified pleural plaques
Pleural nodularity with thickening >1 cm (Correct answer)
Small free-flowing pleural effusion
Costophrenic angle blunting alone

Correct answer: Pleural nodularity with thickening >1 cm

Irregular pleural nodularity and thickening greater than 1 cm are hallmarks of malignancy, while bilateral calcified plaques alone indicate asbestos exposure without malignancy.

Question 80: Benign multicystic peritoneal mesothelioma is distinguished from malignant peritoneal mesothelioma by which feature?

It spreads to the pleura more rapidly
It does not respond to surgery
It is non-invasive and has a favorable prognosis (Correct answer)
It contains sarcomatoid cells

Correct answer: It is non-invasive and has a favorable prognosis

Benign multicystic peritoneal mesothelioma is a non-invasive cystic lesion of the peritoneum with an excellent prognosis compared to its malignant counterpart.

Question 81: Which occupational group carries the highest risk of presenting with mesothelioma symptoms?

Insulation and shipyard workers with asbestos exposure (Correct answer)
Agricultural field workers
Healthcare workers
Office administrative workers

Correct answer: Insulation and shipyard workers with asbestos exposure

Insulation workers, shipyard workers, and others with direct asbestos exposure have the highest lifetime risk of developing mesothelioma.

Question 82: Which MRI sequence is most useful for characterizing the relationship of pleural mesothelioma to the diaphragm?

Diffusion-weighted imaging
STIR sequence
T1-weighted post-contrast
T2-weighted imaging (Correct answer)

Correct answer: T2-weighted imaging

T2-weighted MRI provides excellent contrast between tumor and adjacent structures, helping delineate diaphragmatic involvement.

Question 83: Which IHC marker strongly supports synovial sarcoma over sarcomatoid mesothelioma in a chest wall/pleural spindle cell tumor?

BAP1 loss
Pancytokeratin positivity alone
TLE1 positivity with SYT-SSX fusion on FISH (Correct answer)
D2-40 positivity

Correct answer: TLE1 positivity with SYT-SSX fusion on FISH

TLE1 is a sensitive marker for synovial sarcoma, and the SYT-SSX translocation confirmed by FISH definitively distinguishes it from sarcomatoid mesothelioma.

Question 84: Megakaryocyte potentiating factor (MPF) is a biomarker for mesothelioma that is related to which protein?

BAP1
Fibulin-3
Mesothelin (Correct answer)
Calretinin

Correct answer: Mesothelin

MPF is a precursor of mesothelin and is shed into the blood; it has been studied as a complementary biomarker alongside SMRP for mesothelioma detection.

Question 85: Which mesothelioma cell type accounts for approximately 10–15% of cases and has the worst prognosis?

Biphasic
Sarcomatoid (Correct answer)
Epithelioid
Desmoplastic

Correct answer: Sarcomatoid

Sarcomatoid mesothelioma makes up 10–15% of cases and has the poorest median survival due to resistance to most treatments.

Question 86: Which serum biomarker is most widely used to support a diagnosis of malignant pleural mesothelioma?

CA 19-9
CEA
Mesothelin (SMRP) (Correct answer)
AFP

Correct answer: Mesothelin (SMRP)

Soluble mesothelin-related peptide (SMRP) in serum is the most validated blood biomarker for malignant mesothelioma, approved by the FDA as an adjunct diagnostic tool.

Question 87: CT-guided core needle biopsy of a pleural mass in suspected mesothelioma is preferred over fine needle aspiration (FNA) because:

It avoids radiation exposure
It provides tissue architecture needed for subtyping (Correct answer)
It is less invasive
It provides faster results

Correct answer: It provides tissue architecture needed for subtyping

Core needle biopsy preserves tissue architecture, which is essential for immunohistochemical subtyping (epithelioid vs. sarcomatoid) of mesothelioma.

Question 88: Which blood-based prognostic factor predicts worse outcome in pleural mesothelioma independent of stage?

Normal serum albumin
Absence of anemia
Elevated neutrophil-to-lymphocyte ratio (NLR >5) (Correct answer)
Low platelet count

Correct answer: Elevated neutrophil-to-lymphocyte ratio (NLR >5)

An NLR greater than 5 reflects an immunosuppressive systemic inflammatory state and is an independent predictor of shorter survival in mesothelioma.

Question 89: Which imaging modality is typically the first used when mesothelioma is suspected based on symptoms?

PET scan
MRI
Ultrasound
Chest X-ray (Correct answer)

Correct answer: Chest X-ray

A chest X-ray is the initial imaging tool used when pleural mesothelioma is suspected, often revealing pleural effusion or pleural thickening.

Question 90: Which mesothelial lesion is classified as a precursor to mesothelioma and shows malignant cells confined to the mesothelial surface?

Fibrous pleuritis
Pleural plaques
Reactive mesothelial hyperplasia
Mesothelioma in situ (Correct answer)

Correct answer: Mesothelioma in situ

Mesothelioma in situ (MIS) is a newly recognized WHO entity where malignant mesothelial cells are confined to the surface without stromal invasion, detected by BAP1 loss or CDKN2A deletion.

Question 91: Reactive mesothelial hyperplasia must be distinguished from mesothelioma because:

It is benign and does not require cancer treatment (Correct answer)
It cannot be sampled by biopsy
It always progresses to mesothelioma
It has worse prognosis than mesothelioma

Correct answer: It is benign and does not require cancer treatment

Reactive mesothelial hyperplasia is a benign response to pleural injury and infection; misdiagnosing it as mesothelioma would lead to unnecessary aggressive treatment.

Question 92: A patient presents with progressive dyspnea and is found to have a large right-sided pleural effusion. After thoracentesis, the fluid rapidly re-accumulates within two weeks. This pattern is most consistent with:

Parapneumonic effusion from pneumonia
Chylothorax from lymphatic obstruction
Malignant pleural effusion from mesothelioma (Correct answer)
Transudative effusion from heart failure

Correct answer: Malignant pleural effusion from mesothelioma

Rapid re-accumulation of pleural fluid after thoracentesis is a hallmark of malignant pleural effusion, commonly seen in mesothelioma.

Question 93: Which rare pleural tumor is composed of lipomatous elements and must be distinguished from mesothelioma with lipomatous areas?

Epithelioid hemangioendothelioma
Well-differentiated liposarcoma (Correct answer)
Pleomorphic carcinoma
Desmoid tumor

Correct answer: Well-differentiated liposarcoma

Well-differentiated liposarcoma of the pleura contains mature fat and atypical lipoblasts, which distinguishes it from any fat-containing mesothelioma variant.

Question 94: VEGF (vascular endothelial growth factor) serum levels in mesothelioma are elevated and correlate with:

Sarcomatoid cell type only
Pleural effusion volume and tumor angiogenesis (Correct answer)
Response to surgery
BAP1 mutation status

Correct answer: Pleural effusion volume and tumor angiogenesis

Elevated VEGF promotes tumor angiogenesis and is associated with larger pleural effusions; it has been explored as a therapeutic target in mesothelioma.

Question 95: Which inflammatory marker ratio is used as a prognostic tool in mesothelioma?

ESR alone
Procalcitonin
Ferritin level
Neutrophil-to-lymphocyte ratio (NLR) (Correct answer)

Correct answer: Neutrophil-to-lymphocyte ratio (NLR)

An elevated neutrophil-to-lymphocyte ratio (NLR) reflects systemic inflammation and immune suppression and is an independent prognostic marker in mesothelioma.

Question 96: Horner's syndrome appearing in a patient with pleural mesothelioma most likely indicates:

Paraneoplastic neurological involvement
Chemotherapy-induced peripheral neuropathy
Superior vena cava syndrome
Apical tumor involvement with invasion of the sympathetic chain (Correct answer)

Correct answer: Apical tumor involvement with invasion of the sympathetic chain

Horner's syndrome (ptosis, miosis, anhidrosis) in mesothelioma results from tumor invasion of the sympathetic chain near the apex of the chest.

Question 97: Biphasic mesothelioma contains which combination of cell types?

Both primary and metastatic cells
Both benign and malignant cells
Both epithelioid and sarcomatoid cells (Correct answer)
Both pleural and peritoneal cells

Correct answer: Both epithelioid and sarcomatoid cells

Biphasic mesothelioma is a mixed type containing both epithelioid and sarcomatoid cells, with prognosis depending on which type predominates.

Question 98: Which germline mutation significantly increases the lifetime risk of developing mesothelioma?

BRCA1 mutation
MLH1 mutation
BAP1 mutation (Correct answer)
RB1 mutation

Correct answer: BAP1 mutation

Germline BAP1 mutations define the BAP1 tumor predisposition syndrome, which markedly increases the risk of mesothelioma, uveal melanoma, and other cancers.

Question 99: Cytoreductive surgery plus HIPEC for peritoneal mesothelioma is associated with median survival of approximately:

6–12 months
12–18 months
Over 10 years
40–60 months (Correct answer)

Correct answer: 40–60 months

Complete cytoreductive surgery combined with HIPEC achieves median survival of approximately 40–60 months in selected peritoneal mesothelioma patients.

Question 100: At what stage is mesothelioma most often diagnosed due to the non-specific nature of early symptoms?

Stage II with minimal spread
Stage I with localized disease
Incidentally at Stage I during routine screening
Stage III or IV with advanced disease (Correct answer)

Correct answer: Stage III or IV with advanced disease

Because early symptoms like dyspnea and fatigue are non-specific, most mesothelioma cases are diagnosed at Stage III or IV when disease is already advanced.

Mesothelioma Diagnosis Clinical Knowledge Assessment

Assesses clinical competency in diagnosing malignant mesothelioma, covering diagnostic imaging, biopsy and pathology, biomarker interpretation, and differential diagnosis from adenocarcinoma and benign conditions.

100

Questions

120 min

Time Limit

70%

To Pass

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