To assess underdiagnosing Gleason pattern 5 on needle biopsy and discuss the potential consequences for patient management.

We retrieved 300 consecutive prostate biopsy cases from the consultation files at The Johns Hopkins Hospital (JHH) from 2009-2010 in which we identified Gleason pattern 5. All of these cases were diagnosed by one of the authors and all were sent in as a final diagnosis for which the outside pathologist was not requesting consultation because of difficulty with the diagnosis. The Gleason grades assigned to these cases at our institution were compared with the grade rendered by the submitting pathologists from the outside institution.

In 146 (48.7%) of the cases, Gleason pattern 5 was not identified by the outside pathologists. Of the 146 cases, the outside Gleason score was ≤7 in 61 (20.3%) and 4 + 4 = 8 in 85 (28.4%). Even when the tumor was diagnosed at JHH as Gleason score 5 + 5 = 10, only 26 (41.3%) were diagnosed as the same by the outside pathologists; Gleason score 9 was graded in 27 (42.8%).

Considering the important prognostic and therapeutic implication of misdiagnosing Gleason pattern 5, efforts should be made by the pathology community to acknowledge this as a problem and improve on individual pathologists' accuracy by diverse medical education programs. In addition, urologists should not hesitate in sending biopsies with high-grade prostate cancer for expert genitourinary pathology second opinions.