High Gleason score 8 to 10 adenocarcinoma is the most aggressive and potentially 
lethal form of prostate cancer. The 2005 International Society of Urological 
Pathology (ISUP)-modified Gleason grading scheme defines several gland 
arrangements of high Gleason grade patterns 4 and 5. The aim of this 
investigation was to quantitate the frequency of the ISUP-defined high Gleason 
grade patterns in needle biopsy tissue, to determine the common admixtures and 
to characterize patterns not presented in the 2005 ISUP report. For patients who 
underwent radical prostatectomy, we analyzed for association of specific 
high-grade patterns in needle biopsy with extraprostatic extension in radical 
prostatectomy tissues. A total of 268 prostate needle biopsy cases with Gleason 
score of 8 to 10 were examined. A mean of 3.6 patterns (range, 1 to 8) were 
identified per case and only 12% of cases had a pure single pattern. Ill-defined 
glands with poorly formed lumina (at 57%) and fused microacinar glands (at 53%) 
comprised the predominant and most frequently admixed patterns. Single cells and 
single signet ring cells were present in 53% and 31% of cases, respectively. 
Additional patterns in order of frequency included cords (35%), cribriform 
glands (25%), sheets of cells (19%), chains (4%), glomeruloid (3%), 
comedonecrosis (2%), and hypernephromatoid (1 case=0.3%). Gleason score 8 to 10 
carcinomas are typically extensive in needle core tissue, with a mean of 4.4 
positive cores (range, 1 to 15 cores) per case. Only 14 cases (5%) had 
high-grade minimal carcinoma measuring <1 mm in needle core tissue. Gleason 
grade patterns not described in the 2005 ISUP report include single file growth, 
solid cylinders, and nested patterns. The single file pattern was present in 40% 
of cases, and the small solid nested pattern was detected in 24% of cases. One 
case displayed solid cylinders. Only the single file pattern was associated with 
extraprostatic extension at radical prostatectomy (P=0.005). These results show 
that the 2005 ISUP-defined patterns of high Gleason score 8 to 10 prostatic 
adenocarcinoma can be stratified on the basis of frequency of occurrence in 
needle biopsy tissue. Three patterns not defined in the 2005 ISUP scheme have 
been characterized, including single file, nested, and solid cylinder 
arrangements. As aggressive and potentially lethal prostate cancer is most often 
of Gleason score 8 to 10, it is important for diagnostic recognition purposes to 
be aware of the frequency of various patterns encountered in high Gleason score 
8 to 10 adenocarcinomas, the types of pattern admixtures, and the 
histomorphologic presentation of unusual patterns. We propose that Gleason grade 
assignments should incorporate single file, solid nested, and solid cylinder 
arrangements as high-grade pattern 5 because of the absence of glandular luminal 
space formation.