The reasons behind variation in Gleason grading of prostatic biopsies: areas of agreement and misconception among 266 European pathologists

Aims The Gleason scoring system underwent revision at the International Society of Urological Pathology (ISUP) conference in 2005. It is not known how uropathologists have interpreted its recommendations. Method and results A web‐based survey to European Network of Uropathology members received replies from 266 pathologists in 22 countries. Eighty‐nine per cent claimed to follow ISUP recommendations. Key areas of disagreement included the following. Smoothly rounded cribriform glands were assigned Gleason pattern (GP) 3 by 51% and GP 4 by 49%. Necrosis was diagnosed as GP 5 by 62%. Any amount of secondary pattern of higher grade in needle biopsies was included in the Gleason score by 58%. Tertiary GP of higher grade on needle biopsies was included in the Gleason score by only 58%. If biopsy cores were embedded separately, only 56% would give a Gleason score for each core/slide examined; 68% would give a concluding Gleason score and the most common method was a global Gleason score (77%). Among those who blocked multiple biopsy cores together, 46% would only give an overall Gleason score for the case. Conclusion Misinterpretation of ISUP 2005 is widespread, and may explain the variation in Gleason scoring seen. Clarity and uniformity in teaching ISUP 2005 recommendations is necessary.