Mucous gland metaplasia of the prostate was observed in 11 of the 1,23
6 autopsy cases. The cells were characterized by plump cytoplasmic muc
in and tiny nuclei that were basally oriented. They resembled Cowper's
gland (bulbourethral gland) epithelium. The lesion was located random
ly within the glands and was very small; only one was larger than 1 mm
2. The cytoplasmic mucin was periodic-acid Schiff positive and immunoh
istochemically negative for prostate-specific antigen. Lectin binding
profiles were different from those of normal prostatic glandular epith
elium and also from those of Cowper's gland. The importance of recogni
zing mucous metaplasia lies in its differentiation from other lesions,
especially from low-grade carcinoma.