FLORID HYPERPLASIA OF MESONEPHRIC REMNANTS INVOLVING PROSTATE AND PERIPROSTATIC TISSUE - POSSIBLE CONFUSION WITH ADENOCARCINOMA

Two cases of florid hyperplasia of mesonephric remnants occurring in t he prostate are described. One case was originally interpreted as inva sive adenocarcinoma on transurethral resection (TUR), resulting in rad ical prostatectomy. In the second case, a TUR specimen was diagnostic for adenocarcinoma, which was confirmed in the radical prostatectomy s pecimen. Florid mesonephric hyperplasia in the second case was an inci dental finding. The TUR specimen in the first case and sections of the prostatectomy specimens in both cases contained a proliferation of tu bules, which ranged from aggregates of microacini to dilated structure s containing a characteristic colloid-like material. The location of t hese lesions in the base of the prostate gland and periprostatic soft tissue suggests that these may be mesonephric remnants that have becom e hyperplastic. This type of lesion shares many features with mesoneph ric hyperplasia occurring in the female genital tract, including the p resence of eosinophilic intratubular material and a lobular arrangemen t of microacini lined by a single layer of epithelium with prominent n ucleoli. However, the latter feature, along with the apparent permeati on of the prostatic fibromuscular stroma, periprostatic soft tissue, a nd even neural spaces, closely mimicked prostatic adenocarcinoma. In b oth cases, the proliferating tubules reacted with keratin 903 and were negative for prostate-specific antigen and prostate acid phosphatase, thereby excluding the diagnosis of prostatic adenocarcinoma. We concl uded that lobular hyperplasia of mesonephric remnants is a distinct hi stologic entity that may occur in the prostate and periprostatic soft tissues and closely mimic prostatic adenocarcinoma.