Table 1 Comparison of the features of well differentiated papillary mesothelioma, mesothelioma of uncertain malignant potential and diffuse malignant mesothelioma arising in tunica vaginalis
| Â | Well differentiated papillary mesothelioma | Mesothelioma of uncertain malignant potential | Diffuse malignant mesothelioma |
|---|---|---|---|
Clinical Presentation | Hydrocele | Hydrocele (most often) or scrotal mass (rare) | Hydrocele or scrotal mass with hemorrhagic fluid |
Gross | Single or limited number of small nodules (often pedunculated) | Single or limited number of small nodules (often pedunculated) | Diffuse thickening or multinodular growth (larger or irregular nodules) |
Microscopic Features | Â | Â | Â |
   Papillary architecture | Yes (exclusive) | Yes (dominant) | Yes (focal or rarely dominant) |
   Complex morphology (cribriform, syncitial, solid architecture) | No | Focal | Yes |
   Stromal invasion | No | No | Yes |
   Cell atypia | No | No (or mild) | Yes |
   Mitotic figures | No (or exceptionally rare) | No (or exceptionally rare) | Yes |
   Atypical mitotic figures | No | No | Yes |
   Coagulative necrosis | No | No (or microfocal) | Yes |
   Sarcomatoid growth | No | No | Yes (if present, partial or dominant) |
   Psammoma bodies | No | No | Yes |
Clinical Behaviour | Indolent | Indolent | Aggressive |