Florid cystitis glandularis of intestinal type with mucin extravasation: a mimic of adenocarcinoma.

Six florid examples of cystitis glandularis of intestinal type associated with focal mucin extravasation into the stroma are reported. Several of the cases caused major diagnostic difficulty with regard to their distinction from adenocarcinoma. Five patients had masses that simulated a bladder neoplasm. Patients ranged from 27 to 65 (average 46) years of age and complained of hematuria or irritative symptoms. Four patients were treated only by transurethral resection. One patient underwent partial cystectomy because of an erroneous diagnosis of adenocarcinoma and another total cystectomy because of a neurogenic bladder. Microscopic examination showed numerous glands lined by intestinal type epithelium, conforming to the appearance of the intestinal variant of cystitis glandularis. All cases had at least a minor component of typical cystitis glandularis, and it was prominent in four cases. All six cases had foci of basophilic mucin in the stroma, and this was prominent in four cases. Rounded aggregates of mucin were occasionally surrounded by compressed connective tissue cells, simulating mucinous cysts. In favour of a benign interpretation were the absence of epithelial cells in the extravasated mucin, the lack of atypicality of the cells lining the intestinal type glands in all but one case, a generally orderly distribution of the glands, and their lack of infiltration of the muscularis propria, although they abutted the latter in several cases. Follow-up from 2 to 14 years is available for three of the cases and has been uneventful, the longest follow-up being in the case diagnosed as adenocarcinoma. These cases illustrate the extent to which cystitis glandularis may mimic a neoplasm on gross evaluation and the propensity of mucin extravasation to cause diagnostic difficulty, a finding documented only rarely previously.