LIPOFUSCIN PIGMENTATION (SO-CALLED MELANOSIS) OF THE PROSTATE

Although intraepithelial pigment in the prostate gland has been termed melanosis, the nature of the pigment is not entirely clear, and many pathologists are not aware of its existence. We examined 863 hematoxyl in and eosin (H + E) stained slides from 150 surgical specimens of pro state (69 needle biopsies, 66 transurethral resections, 14 radical pro statectomies, and 1 suprapubic prostatectomy) from 149 patients (age r ange, 47 to 90 years; mean 70 years) in an effort to characterize this pigment. The 1-3 mu m in diameter, predominantly subnuclear, yellow-b rown to gray-brown granules with a dark blue rim (by H + E) stained po sitively with Fontana-Masson, periodic acid-Schiff with diastase, Cong o red, luxol fast blue, and oil-red-O and exhibited yellow autofluores cence consistent with lipofuscin. H + E stained slides revealed pigmen t in the benign epithelium in 86 of 150 cases (57%), within stromal ma crophages in eight cases, and in atypical epithelium in two cases of h igh-grade prostatic intraepithelial neoplasia. Ten cases of invasive a denocarcinoma without recognizable pigment in H + E stained sections w ere stained by the Fontana-Masson technique, and pigment was identifie d in malignant epithelium in three of these cases. Ultrastructural exa mination of intraepithelial pigment in KII-fixed tissue from three rad ical prostatectomy specimens demonstrated the typical appearance of li pofuscin. Although intraepithelial pigment in prostatic biopsy or rese ction specimens is usually considered characteristic of seminal vesicl e epithelium, our study demonstrates that lipofuscin is commonly prese nt in epithelial cells of benign prostatic hyperplasia and less freque ntly in those of prostatic intraepithelial neoplasia and adenocarcinom a. The recognition of this pigment is important in preventing diagnost ic confusion with seminal vesicle epithelium and with melanocytic lesi ons.