Micropapillary bladder carcinoma: A clinicopathological study of 20 cases

Purpose: Micropapillary bladder carcinoma is rare, with only 18 cases repor ted to date. We report 20 additional cases with long-term followup. Materials and Methods: A total of 680 patients with an initial diagnosis of bladder carcinoma in western Sweden in 1987 and 1989 were prospectively re gistered. The clinical records of all 816 patients with bladder cancer trea ted at Sahlgrenska University Hospital with external beam irradiation betwe en 1962 and 1989 were reviewed. The histopathological material was reviewed and immunohistochemical analyses were performed on 20 cases identified wit h micropapillary bladder carcinoma. Results: The incidence of micropapillary bladder carcinoma was 0.7%. Mean p atient age at diagnosis was 69 years (range 45 to 82) and the male-to-femal e ratio was 2.3:1. All but 5 patients had stage T3a disease or higher. Ther e was no difference in stage or prognosis between the 5 prospectively ident ified patients and those treated with external beam irradiation. Only 2 pat ients had micropapillary bladder carcinoma as the only pattern, while 1 had 10% and the remainder had 20 to 95% micropapillary bladder carcinoma. Tran sitional cell carcinoma was noted in 17 patients and 5 had areas of gland f orming adenocarcinoma. Carcinoma in situ was noted in 13 patients and 15 ha d lymphatic invasion. Only 5 patients survived 5 years, 1 of whom died of b ladder cancer after 7 years. Radiation and chemotherapy did not seem to be effective. Conclusions: The light microscopic appearance, which is strikingly similar to ovarian papillary serous carcinoma, and immunohistochemical staining pat tern lend some support to tale theory that micropapillary bladder carcinoma is a variant of adenocarcinoma. Since even tale focal presence of micropap illary bladder carcinoma is associated with a poor prognosis, recognition o f this entity is important. Due to its rarity, the optimal treatment of mic ropapillary bladder carcinoma needs to be determined in a multicenter study .