The Gleason pattern 4 in radical prostatectomy specimens in current practice - Quantification, morphology and concordance with biopsy

Purpose: The upgrading of a prostate acinar adenocarcinoma grade group 1 (GG1) between needle biopsy and prostatectomy is common. The extent of high-grade tumor and cribriform morphology are currently suggested as prognostic factors. Methods: We reviewed 159 prostatectomy specimens from a private laboratory and an academic/public institution in Salvador, Bahia. Results: Tumors signed as GG1 at biopsy were upgraded in 59% of all cases. These tumors showed a low frequency of non-focal extraprostatic extension (one case, 3%), extensive positive surgical margins (two cases, 6%) and seminal vesicle invasion (one case, 3%). Among GG2 and GG3 tumors at prostatectomy, the percentage of Gleason pattern 4 (Gp4) involving the gland at <= 1%, 2-5% and > 5% was associated with extensive extraprostatic extension (9%, 8% and 42%, respectively) and seminal vesicle invasion (1%, 10% and 31%, respectively). The volume of Gp4 of <= 1 ml, > 1 to 2 ml and > 2 ml was associated with extensive extraprostatic extension (8%, 26% and 38%, respectively), seminal vesicle invasion (2%, 21% and 33%, respectively) and nonfocal positive surgical margins (12%, 26% and 29%, respectively). Some GG2 tumors (similar to 20%) indeed showed at least one measurement of Gp4 higher than one quarter of GG3 carcinomas. Cribriform morphology showed no significant associations for other adverse pathologic prognostic factors. Conclusion: Upgrading from GG1 to GG2 is associated with a very low frequency of morphologic features associated with poor prognosis. Routine quantification of Gp4 is feasible in radical prostatectomy products and seems to better stratify tumors regarding the association with other morphologic parameters of prognostic importance.