Mesothelioma Diagnosis Biopsy and Pathology 2 — Questions and Answers
Question 1: Which stain is used on routine pathology sections to first evaluate suspected mesothelioma?
- Hematoxylin and eosin (H&E) (Correct answer)
- PAS stain
- Masson trichrome
- Sudan black
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 2: Which IHC marker is typically negative in mesothelioma but positive in metastatic breast carcinoma to the pleura?
- GATA3 (Correct answer)
- Calretinin
- WT1
- D2-40
Correct answer: GATA3
GATA3 is expressed in breast and urothelial carcinoma but is absent in mesothelioma, making it useful in distinguishing pleural metastases from primary mesothelioma.
Question 3: D2-40 (podoplanin) IHC staining in mesothelioma primarily highlights which feature?
- Lymphatic differentiation and mesothelial cells (Correct answer)
- Vascular endothelium
- Necrosis zones
- Mitotic figures
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 4: FISH (fluorescence in situ hybridization) for CDKN2A (p16) deletion is used in mesothelioma pathology to:
- Distinguish malignant mesothelioma from benign mesothelial hyperplasia (Correct answer)
- Determine asbestos fiber type
- Assess treatment response
- 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 5: In sarcomatoid mesothelioma, which IHC marker is most reliably positive?
- Pancytokeratin (Correct answer)
- Calretinin
- WT1
- D2-40
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 6: What is the significance of the NF2 gene mutation in mesothelioma pathology?
- It is one of the most common somatic mutations found in mesothelioma (Correct answer)
- It predicts response to immunotherapy
- It indicates asbestos-free etiology
- 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.
Mesothelioma Diagnosis Biopsy and Pathology 2
Which stain is used on routine pathology sections to first evaluate suspected mesothelioma?