| Rounded aggregates of urothelial cells which bud from the
surface epithelium are found, in variable numbers, in most bladders
particularly in the trigone. They are without significance except when the
proliferation (proliferative cystitis) is sufficiently florid as to
produce a localized sessile or polypoid mass that will mimic a neoplasm
(Fig. 1, Fig. 2). Tumor-like aggregates of von Brunn nests have some
similarities to the inverted papilloma but lack the branching or
anastomosing feature of the latter. Figure 3 is poliferative cystitis;
Figure 4 is an inverted papilloma. Nests that show size variation and
dispersion in the lamina propria will usually show some nuclear atypia and
represent the nested variant of urothelial carcinoma (Fig. 5). |
