Mesothelioma Diagnosis Biopsy and Pathology 1 — Questions and Answers
Question 1: Which procedure is considered the gold standard for diagnosing malignant pleural mesothelioma?
- Video-assisted thoracoscopic surgery (VATS) biopsy (Correct answer)
- Thoracentesis alone
- CT-guided FNA
- Bronchoscopy
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 2: Immunohistochemistry (IHC) is essential in mesothelioma pathology primarily to:
- Distinguish mesothelioma from adenocarcinoma (Correct answer)
- Measure tumor size
- Assess vascular invasion
- Determine asbestos fiber burden
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 3: Which IHC marker is characteristically positive in epithelioid mesothelioma?
- Calretinin (Correct answer)
- TTF-1
- CEA
- Napsin A
Correct answer: Calretinin
Calretinin is a highly sensitive and specific positive marker for mesothelioma and is routinely included in diagnostic IHC panels.
Question 4: TTF-1 (thyroid transcription factor-1) positivity in a pleural biopsy would support a diagnosis of:
- Metastatic lung adenocarcinoma (Correct answer)
- Epithelioid mesothelioma
- Sarcomatoid mesothelioma
- 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 5: What is the minimum tissue requirement for a definitive mesothelioma diagnosis according to current guidelines?
- Core biopsy with sufficient tissue for IHC (Correct answer)
- Cytology from thoracentesis alone
- Fine needle aspirate only
- Imaging findings without biopsy
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 6: 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 indicates favorable prognosis
- It is present in all benign pleural disease
- It rules out sarcomatoid differentiation
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.
Mesothelioma Diagnosis Biopsy and Pathology 1
Which procedure is considered the gold standard for diagnosing malignant pleural mesothelioma?