Histopathology of a pleural-based lung tumor in a 60-year-old shipyard worker shows biphasic morphology with epithelioid cells forming tubulo-papillary structures and spindle-shaped sarcomatoid areas. Immunostaining shows calretinin and WT1 positivity. What is the diagnosis?
- A Malignant mesothelioma ✓
- B Biphasic synovial sarcoma
- C Metastatic adenocarcinoma
- D Pleomorphic carcinoma
Correct answer: A. Malignant mesothelioma
Explanation
Malignant mesothelioma arises from mesothelial cells of the pleura and is strongly associated with asbestos exposure, typically presenting decades after exposure. Biphasic histology with both epithelioid and sarcomatoid components is characteristic. The immunophenotype is positive for mesothelial markers (calretinin, WT1, podoplanin/D2-40) and negative for adenocarcinoma markers (CEA, TTF-1, MOC-31), distinguishing it from metastatic carcinoma.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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