Mucous gland metaplasia of the prostate

Mucous gland metaplasia of the prostate was observed in 11 of the 1,236 autopsy cases. The cells were characterized by plump cytoplasmic mucin and tiny nuclei that were basally oriented. They resembled Cowper's gland (bulbourethral gland) epithelium. The lesion was located randomly within the glands and was very small; only one was larger than 1 mm2. The cytoplasmic mucin was periodic-acid Schiff positive and immunohistochemically negative for prostate-specific antigen. Lectin binding profiles were different from those of normal prostatic glandular epithelium and also from those of Cowper's gland. The importance of recognizing mucous metaplasia lies in its differentiation from other lesions, especially from low-grade carcinoma.