Micropapillary transitional cell carcinoma of the urinary bladder: report of two cases.

Micropapillary carcinoma is an uncommon variant of urothelial carcinoma with apparent high metastatic potential. The reported cases in the literature were associated with high grade and stage of disease at presentation and a poor prognosis. Micropapillary carcinoma is considered a tumor with an aggressive behavior, even though the morphology may be deceptive. The presence of a micropapillary carcinoma component in bladder biopsies should alert the urologists to the potential of higher stage disease and deep biopsies should be obtained. Two cases of micropapillary carcinoma of the urinary bladder were presented. A 71-year-old woman and a 68-year-old man presented with urinary symptoms. Cystoscopy revealed a papillary tumor on the bladder wall in both cases. Pathologic examination of transurethral resection specimen showed an invasive micropapillary carcinoma; small solid nests lying in small clear spaces that were not stained with antibody CD34. Thus, the lacunar histological pattern did not appear to represent invasion of vascular spaces. Only one case showed an association with urothelial carcinoma. No case showed muscle invasion. No recurrence or metastasis were observed after the initial diagnosis in the two cases.