Comments:
Both nested variant of urothelial carcinoma and florid von Brunn nest hyperplasia (shown here) can lack cytologic atypia. Features supporting nested urothelial carcinoma include: small, crowded nests with variable spacing, infiltrative base, muscularis propria invasion, higher MIB-1 expression. Volmar K, et al. Am J Surg Pathol 2003; 27(9):1243-52.return to Benign Urothelium
