ABSTRACT
Prostate Specific Antigen (PSA) is regarded as a specific marker of prostatic epithelium and has never been detected by immunocytochemistry in extra-prostatic tissues. The casual finding of a strong positivity for polyclonal antisera to PSA in a sweat gland carcinoma prompted a study on a series of skin adnexial and breast specimens (normal and neoplastic). Normal axillary and perineal apocrine sweat glands, some apocrine foci in fibrocystic breast disease and two sweat gland and two breast apocrine carcinomas were stained by several PSA antisera; a recently introduced monoclonal to PSA, however, was unreactive. These observations cast doubt on the specificity of PSA for prostatic epithelium, especially when polyclonal antisera are employed. Immunocytochemical reactions obtained with PSA, in the investigation of skin, lesions must be interpreted with caution and confirmed if necessary with monoclonals to PSA and with PAP.
