Sclerosing adenosis of the prostate gland. A clinicopathological and immunohistochemical study of 11 cases.

Eleven cases of sclerosing adenosis of the prostate gland, a recently reported uncommon pseudoneoplastic lesion with characteristic histological, histochemical, and immunohistochemical features, are described. The well-circumscribed cellular lesions were composed of variably sized and shaped, often compressed, glands and small clusters of epithelial cells embedded in a cellular, often myxoid stroma. Mild cytologic atypia was occasionally present, and one case had moderate cytologic atypia. A distinct basement membrane often surrounded the glands and clusters. Luminal acid mucin was typically present. Keratin-positive basal cells were present in the glands and as spindle cells in the stroma. The basal cells were also immunoreactive for S-100 and muscle-specific actin, suggesting myoepithelial differentiation. Clinical follow-up has shown no evidence of prostatic carcinoma. The available evidence suggests that sclerosing adenosis of the prostate gland is a benign lesion with distinctive features that should enable it to be distinguished from prostatic adenocarcinoma.