Involucrin expression in urinary bladder carcinoma.

Expression of involucrin was investigated immunohistochemically in 27 cases of urinary bladder carcinoma. Although no keratinization was observed in the transitional cell carcinomas examined all displayed involucrin staining to various degrees. Involucrin expression in foci of G-I transitional cell carcinomas was classified into 3 types: type 1, a mixture of intensely stained and slightly positive cells; type 2, highly positive cells intermingled with negative tumour cells; and type 3, all tumour cells slightly positive. Undifferentiated cell carcinomas demonstrated an irregular distribution of involucrin of varying staining intensity while deposition in squamous cell carcinomas was limited to keratinized areas.