Inverted Papilloma
Differential Diagnosis
- Florid von Brunn nests and cystitis cystica/glandularis
- Nested variant urothelial carcinoma
- Inverted urothelial carcinoma
| Inverted Papilloma | Florid von Brunn Nests, Cystitis Cystica/Glandularis |
|---|---|
| Regular pattern of anastomosing cords and trabeculae | Round nests, may show fusion |
| Peripheral palisading and central streaming | Lacks biphasic palisading/streaming pattern |
An older description of inverted papilloma composed of cystic nests (Kunze) may not be separable from florid von Brunn nests
| Nested Variant Urothelial Carcinoma | Inverted Papilloma |
|---|---|
| Overall invasive pattern, not circumscribed | Circumscribed (if sample permits assessment) |
| May involve muscularis propria | Does not involve muscularis propria |
| Varying sizes and shapes of nests | Uniform trabeculae and cords |
| Disorder of cells in nests | Orderly peripheral palisading and central streaming |
| Urothelial Carcinoma with Inverted Growth Pattern | Inverted Papilloma |
|---|---|
| Usually has a surface papillary component | Surface everted papillary component absent or minimal |
| Cytologic features and disorder of carcinoma, appropriate to grade | Bland, uniform, orderly cells |
| Mitotic figures present, appropriate to grade | No mitotic figures |
