Answer: Prostatic duct adenocarcinoma

Histology: Although most adenocarcinomas of the prostate are of the acinar type, a minority (like the current example) are composed of papillary or cribriform structures lined by distinctively bland tall columnar cells characteristic of ductal type prostatic carcinoma.

Discussion: Centrally located ductal adenocarcinomas of the prostate are exophytic lesions present in and around the verumontanum and typically are diagnosed on transurethral resection. Although some of these exophytic tumors may be relatively indolent, most prostatic duct adenocarcinomas are expected to behave in an aggressive fashion. Lesions involving the peripheral zone of the prostate may not have a urethral component and are usually diagnosed on needle biopsies. In the largest needle biopsy series by Brinker et al., the authors concluded that prostatic ductal adenocarcinoma seen on needle biopsy may represent a more advanced disease with a shortened time to progression. Therefore, these lesions are considered by most to be equivalent to a Gleason Score 8 in terms of biologic behavior. In addition to cribriform or papillary structures, discrete glands lined by tall columnar cells with occasional stratification mimicking high grade PIN can be present. A coexisting acinar carcinoma component is identified in almost half of the cases. Like its acinar counterpart, prostatic duct adenocarcinoma demonstrates positive reactivity for PSA and PSAP. Unlike acinar prostatic adenocarcinoma however, the presence of scattered residual basal cells on high molecular weight cytokeratin or p63 stains should not exclude the diagnosis of carcinoma given the retention of such basal layer in some of these neoplasms.

Reference(s):
– Brinker DA, Potter SR, Epstein JI. Ductal adenocarcinoma of the prostate diagnosed on needle biopsy: correlation with clinical and radical prostatectomy findings and progression. Am J Surg Pathol. 1999;23(12):1471-9.