Mesothelioma: High-Yield Pathology
Mesothelioma is a malignant neoplasm arising from the mesothelial cells of the pleura, peritoneum, or pericardium. It is strongly and specifically associated with chronic asbestos exposure.
1. Pathogenesis and Morphology
- Asbestos Exposure: Unlike bronchogenic carcinoma (where smoking acts synergistically with asbestos), the risk of mesothelioma is almost exclusively linked to the intensity and duration of asbestos exposure, not smoking.
- Macroscopic: Typically presents as a thick, gelatinous, gray-white tumor that encases the lung (pleural rind).
- Microscopic: Classified into three main histological patterns: epithelioid (most common), sarcomatoid, and biphasic.
2. Exam Must-Knows
| Diagnostic Marker | Clinical Importance |
|---|---|
| Calretinin (+), CK5/6 (+) | Immunohistochemical markers used to confirm mesothelial origin. |
| CEA (-), TTF-1 (-) | Used to rule out adenocarcinoma (which is TTF-1 positive). |
3. Clinical Pearl
Pathology Board Hint: Always remember the long latency period—mesothelioma often develops 20 to 40 years after the initial asbestos exposure. Clinical presentation includes recurrent pleural effusions and chest pain.