Adenoid cyst-like carcinoma of the prostate is a rare but distinctive
variant of prostatic adenocarcinoma. Adenoid cystic carcinoma is most
commonly encountered in the salivary glands, and the cell of origin is
thought to be the myoepithelial cell. Electron microscopic studies of
the human prostate have not revealed myoepithelial differentiation. M
yoepithelial cells of the human prostate are thought to arise in serom
ucinous ectopic glands. A case of adenoid cyst-like carcinoma of the p
rostate gland is documented, and the histological, immunohistochemical
, and electron microscopic features of this tumor are discussed. These
features are compared with five cases of classic salivary gland adeno
id cystic carcinoma. To define the myoepithelial cell population of th
e prostate gland, 12 normal prostate glands were studied. Prostatic ad
enoid cyst-like carcinoma differs from adenoid cystic carcinoma of sal
ivary gland origin, and it is therefore postulated that the behavior o
f these tumors may likewise differ.