Answer: Adenocarcinoma, Gleason score 2+2=4

Histology: There is a nodule of closely packed glands which on one chip can be appreciated as having a lobular circumscribed border. The glands are tightly packed with little intervening stroma. There is minimal variation in gland size from one to the other. At higher magnification, most of the glands have dense, intraluminal eosinophilic secretions admixed with blue-tinged mucinous secretions. The glands have sharp straight luminal borders. Nuclei are enlarged with prominent nucleoli.

Discussion: The features in this case are typical of adenocarcinoma of the prostate. The question with this case pertains to its grade. In contrast to a Gleason 1+1=2 tumor, these glands show greater variation in size from one to the other. Gleason score 1+1=2 tumors are virtually almost never seen and, if present, are usually only a focal component of a higher grade tumor. Gleason score 3+3=6 tumors would not show a circumscribed nodule as in the current case. Furthermore, Gleason score 3+3=6 tumors are characterized by smaller glands in addition to the glands infiltrating between benign glands. The hallmark of Gleason pattern 2 is glands that are larger than the typical Gleason pattern 3 cancers closely packed in a relatively circumscribed nodule. They have somewhat more variability in size from one to the other vs. Gleason pattern 1. Whether the tumor is truly Gleason score 1+1=2 or 2+2=4 is of no clinical significance. Gleason scores 2 through 4 are considered together as a group of low grade carcinomas. Whereas Gleason scores 2 through 4 cancers are virtually never seen on needle biopsy, they are not uncommonly seen on TURP performed incidentally for lower urinary tract symptoms. If low-grade adenocarcinoma is incidentally found on a TURP, especially in an older man, and the tumor is of limited quantity (less than 5%), most of these patients will not be treated with definitive therapy. If such a carcinoma were found in a younger individual, one might consider a range of therapy from observation to an aggressive option with radical prostatectomy for prevention of future progression. Another option would be needle biopsy of the prostate to assess for a peripheral zone intermediate grade cancer component, which, if present, would lead to definitive therapy. Also factored in are the post-TURP serum PSA levels. If the post-TURP serum PSA levels are very elevated (greater than 10 ng/ml), one might assume that there is a significant amount of residual tumor and that could also lead to definitive treatment. The Gleason scores are assigned based on the architectural pattern without regard to the cytology.