A 65-year-old former asbestos worker develops a pleural tumor with epithelioid and sarcomatoid components. Immunohistochemistry shows calretinin+, WT-1+, CK5/6+, CEA- staining. The diagnosis is:
- A Pleural metastasis from adenocarcinoma
- B Solitary fibrous tumor of the pleura
- C Malignant mesothelioma ✓
- D Pleural synovial sarcoma
Correct answer: C. Malignant mesothelioma
Explanation
Malignant mesothelioma is confirmed by the immunoprofile showing positivity for mesothelial markers (calretinin, WT-1, CK5/6) and negativity for adenocarcinoma markers (CEA, TTF-1, Napsin A). Mesothelioma is strongly associated with asbestos exposure (amphibole type, especially crocidolite) with a latency of 25-45 years. Biphasic patterns with epithelioid and sarcomatoid components are classic. CEA positivity would favor adenocarcinoma.
Reference: Robbins & Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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