Prostatic Adenocarcinoma: Gleason Grading (Modified Grading by ISUP)
Based purely on architecture, classified into 5 patterns or grades (1 to 5) representing a spectrum from better-differentiated well-formed glands to poorly differentiated cancer incapable of forming glands.
After its development by Dr. Donald Gleason in 1966, underwent refinements in 1974 and 1977 (image A), and had its latest modification in 2005 by ISUP (image B).
In case there are 3 different grades, a tertiary pattern is included if it is higher than the secondary grade.
Primary grade: most predominant.
Secondary grade: highest non-predominant pattern.
Gleason 3 (60%) and Gleason 4 (40%).
In prostatectomy and biopsy: Gleason 3+4=7.
Gleason 3 (100%). (If pure, the only pattern present is doubled).
In prostatectomy and biopsy: Gleason 3+3=6.
Gleason 3 (60%), Gleason 4 (30%) and Gleason 5 (10%).
In prostatectomy: Gleason 3+4=7, with tertiary pattern 5.
In biopsy: Gleason 3+5=8.
In biopsy, GS is assigned to each separately designated prostate subsite.
ISUP 2005 modifications take into account grading of variants of prostate carcinoma and unusual morphologies, such as
Ductal adenocarcinoma, considered as Gleason grade 4 (GS 8 if pure).
Pseudohyperplastic variant, graded as Gleason score 3+3=6.
Mucinous fibroplasia is subtracted and gland graded (mostly Grade 3).