Further observations on histological changes at the ureteroileal junction in ileal conduits.

Seventy-two ureteroileal anastomoses taken from ileal conduits removed from 62 patients were examined histologically to characterize the range of mucosal and stromal changes at these sites. All 72 demonstrated variable amounts of subepithelial chronic inflammation and fibrosis. Other histological features included: cystic spaces lined by transitional epithelium (N = 29; 40%; average diameter 1.2 mm); cystic spaces lined by mixed intestinal/transitional epithelium (N = 5; 7%; average diameter 0.77 mm); and cystically dilated intestinal glands (N = 21; 29%; average diameter 0.24 mm). The latter were associated with overgrowth by transitional epithelium, which had prevented mucus drainage. Twenty-one (29%) had mucus pools with no epithelial lining (average diameter 1.2 mm), and polypoidal protrusions into the lumen of the anastomosis were found containing mucus pools (N = 4; 6%; average diameter 1.4 mm), transitional-lined cysts (N = 5; 7%; average diameter 2.2 mm), and mixed intestinal/transitional-lined cysts (N = 2; 3%; average diameter 2.5 mm). Focal rupture of dilated intestinal glands with interstitial pooling of mucus was not uncommon, and marked dystrophic calcification was found in 1 case within a large collection of extracellular mucus. This series confirms that inflammation, fibrosis, and glandular overgrowth by transitional epithelium are common occurrences at ureteroileal anastomosis sites. Subsequent gland rupture may result in sizable accumulations of interstitial mucus, and rarely in marked dystrophic calcification.