Immunohistochemical distribution of epithelial membrane antigen in bladder carcinomas as detected with a monoclonal antibody.

Expression of epithelial membrane antigen (EMA) was investigated immunohistochemically in 27 cases of bladder carcinoma using a monoclonal antibody. Normal urothelial epithelium showed EMA staining restricted to the upper layer of the surface epithelium. G-I transitional cell carcinomas demonstrated positive EMA staining which could be divided into the following 3 types; type 1, in which highly stained cells occurred in the upper layer of the neoplastic epithelium; type 2, in which the whole tumour focus was slightly stained; and type 3, in which cells strongly positive for EMA were scattered throughout the tumour focus. G-III (undifferentiated) transitional cell lesions exhibited irregular expression of EMA whereas squamous cell demonstrated specific intense EMA staining within keratinized tumour cells.