Adenoid cyst-like carcinoma of the prostate gland.

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. Myoepithelial cells of the human prostate are thought to arise in seromucinous ectopic glands. A case of adenoid cyst-like carcinoma of the prostate 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 adenoid cystic carcinoma. To define the myoepithelial cell population of the prostate gland, 12 normal prostate glands were studied. Prostatic adenoid cyst-like carcinoma differs from adenoid cystic carcinoma of salivary gland origin, and it is therefore postulated that the behavior of these tumors may likewise differ.