Basal cell hyperplasia of the prostate.

Basal cell hyperplasia of the prostate is a rare, benign lesion that often has been misdiagnosed as adenocarcinoma. Thirteen cases of basal cell hyperplasia were reviewed. All of the patients were over 60 years of age (range 63-83) and all had benign prostatic hypertrophy in addition to basal cell hyperplasia. Histologic features consisted of nests of uniform small cells with scant cytoplasm forming solid nests and acinar structures. Some foci had nodular configurations and most were located within larger nodules of "typical" glandular hyperplasia. In some instances there was a merging of the two types of hyperplasia. There was neither nuclear atypia nor pleomorphism, and the adjacent stroma was hyperplastic. Small elongated cells with desmosomes and nonspecific, dense bodies were seen on electron microscopic studies of formalin-fixed material. The architectural and cytologic features of the basal cell proliferations were not those of carcinoma. However, synchronously, two patients demonstrated foci of prostate carcinoma unrelated to the basal cell hyperplasia.