Table 1 Morphological subclassification of epithelioid and sarcomatoid mesotheliomas.
From: Pleural mesothelioma classification—update and challenges
Subtype | Architecural patterns | Cytological features | Stromal features | Grade |
|---|---|---|---|---|
Epithelioid | • Tubulopapillary • T rabecular • Adenomatoid • Solid • Micropapillary | • Rhabdoid • Deciduoid • Small cell • Clear cell • Signet ring • Lymphohistiocytoid • Pleomorphic | • Myxoid | • Low grade -Any nuclear grade I - Nuclear grade II without necrosis • High grade -Nuclear grade II with necrosis - Any nuclear grade III Nuclear grade: Nuclear atypia score: 1 mild, 2 moderate, 3 severe Mitotic count score: 1 low (≤1 mitosis/2 mm2) 2 intermediate (2–4 mitosis/2 mm2) 3 high (≥5 mitosis/2 mm2) Sum: Nuclear grade I (sum 2 or 3) Nuclear grade II (sum 4 or 5) Nuclear grade III (sum 6) |
Sarcomatoid | • None | • Lymphohistiocytoid • Transitional • Pleomorphic | • Desmoplastic • With heterologous differentiation | • None |
