Paneth cell-like metaplasia of the prostate gland

We report two cases of Paneth cell-like metaplasia of the prostate gland, one in poorly differentiated carcinoma and the second in benign hyperplasia. By light microscopy, the Paneth-like cells were indistinguishable from Paneth cells found in the normal small intestine and ultrastructurally showed electron-dense granules typical of Paneth cells. Immunohistochemical stains were positive for prostate-specific antigen and prostatic acid phosphatase and negative for lysozyme and α₁-antitrypsin. The clinical significance of Paneth cell-like metaplasia is unknown and may represent an example of the multipotential metaplastic capability of actively dividing cells.