Chronic interstitial cystitis: a heterogeneous syndrome.

A series of 28 patients with interstitial cystitis and 14 healthy volunteers were studied. We found marked histopathological differences between classic (ulcerative) interstitial cystitis and early (nonulcerative) interstitial cystitis. The bladder mucosa of patients with classic disease exhibited focal ulceration, edema and perineural-perivascular infiltrates. There was a marked increase in 2 distinct mast cell populations. Mast cells increased in the detrusor muscle and mucosa. Mucosal mast cells, unlike those in the muscular coat, are susceptible to aldehyde fixation, and require special fixation and staining techniques for proper demonstration. These cells were numerous in the epithelium and were recovered in bladder washings, consistent with the finding that they have a migratory capacity. In nonulcerative interstitial cystitis all signs of mast cell activation were absent, and the histopathological changes were few and fairly uncharacteristic. We also observed some marked clinical differences between ulcerative and nonulcerative interstitial cystitis. These 2 conditions appear to represent separate entities and should be evaluated separately in clinical studies.