Comparison of prostatic adenocarcinoma Gleason 5 and intraductal carcinoma of the prostate with tumor necrosis. A morphometric study.

Intraductal carcinoma of the prostate(IDCP) is defined as a solid or cribriform neoplastic growth confined to ducts and acini, with preservation of the basal cell layer. Since IDCP can often present tumor necrosis (TN), it should be distinguished from Gleason 5 (GP5) invasive adenocarcinoma for staging and clinical purposes. In the present study we reviewed 344 radical prostatectomies performed at our institution and selected all cases with either >5% GP5 or IDCP for assessment of TN on histology slides (n = 59). A total of 19 cases with TN were identified, and morphology, size, location, and histoarchitecture of the lesions with TN were recorded. Subsequently, the corresponding sections were stained with a basal cell immunomarker (P63), and lesions with TN were assigned to IDCP or invasive carcinoma GP5 for comparison. Our results show that a branched shape and size 501-1000 μm are more common in IDCP, while a size >1000 μm and location within 1 mm of the periprostatic soft tissue are significantly more prevalent in invasive adenocarcinoma GP5. These features, however, usually cannot be assessed in core biopsies. In this setting, the utilization of immunohistochemistry is warranted to differentiate IDCP and GP5 with necrosis.