Inflammatory pseudotumor of the ureter and the urinary bladder.

Inflammatory pseudotumor (IPS) of the urinary bladder was first described in 1980. We report four cases of IPS which occurred during the last four years. One tumor occurred in the bladder of a 49-year-old woman five months after abdominal hysterectomy of uterine leiomyomas, two tumors in a 35- and 39-year-old woman, respectively, without antecedental surgical intervention (though one with recidive after six months). The fourth occurred in a 64-year-old male in the proximal ureter by pyelonephritis. Two cases were initially diagnosed at frozen section during operative treatment, the others on paraffine section after immunohistochemical examination. Two cases showed an aberrant expression of cytokeratines. There is no evidence of recidive tumor within a mean follow up of 25 months (12-49 months). Features to differentiate benign from malignant spindle cell lesions of the lower urinary tract are the absence of atypical mitoses, significant cytologic atypia, absence of necroses within the tumor (rather on its surface), no destructive growth at the tumor margins and low cellularity. Usually, IPS show a submucosal edematous area with a deeper, highly cellular component. The clinical history of a recent bladder operation or gynecologic surgery is of upmost importance in making the diagnosis of IPS. Complete surgical excision, either by transurethral resection or partial cystectomy appears to be curative for IPS.