Invasive micropapillary carcinoma of the urinary bladder: an immunohistochemical study of neoplastic and stromal cells.

A 66-year-old man complained of hematuria. A cystoscopy revealed a non-papillary tumor and radical cystectomy was performed. Macroscopically, an ulcerative lesion was observed. Microscopically, the neoplasm showed a mixture of urothelial carcinoma, squamous cell carcinoma and micropapillary carcinoma. Immunohistochemically, micropapillary carcinoma cells were positive for cytokeratins 7 and 20, carcinoembryonic antigen and CA125. Additionally, myofibroblasts were distributed in a chicken-wire pattern in the stroma of micropapillary carcinoma. Subsequently, the patient died of carcinoma 1 year after the onset of symptoms. Our results support the previous hypothesis that bladder micropapillary carcinoma runs an aggressive clinical course and suggest that micropapillary carcinoma may show the glandular differentiation of urothelial carcinoma and show the stromal reaction by myofibroblasts resembling that of carcinoma in other anatomic sites.