[819] Usual and Unusual Histologic Patterns of Gleason Score 8-10 Adenocarcinoma of the Prostate.

Srinivas Gottipati, Jason C Warncke, Peter A Humphrey. Washington University Medical Center, MO

Background: The 2005 International Society of Urological Pathology (ISUP) modified Gleason grading scheme defines several gland arrangements of Gleason patterns 4/5. For pattern 4 these are fused microacinar glands, ill defined glands with poorly formed glandular lumina, large cribriform glands, cribriform glands with an irregular border, and hypernephromatoid. For pattern 5 these are solid sheets, cords, or single cells and comedocarcinoma. Scant data exist on the frequency of occurrence of these patterns. This aim of this study was to ascertain the frequency of the defined patterns in needle biopsy tissue, to determine the common admixtures, and to define patterns not in the 2005 ISUP report.
Design: 136 needle biopsy cases with a Gleason score (GS) of 8-10 were examined. We quantitated the number and type of ISUP patterns present for each case, determined extent of core involvement, and assessed for patterns not described in the 2005 ISUP system.
Results: A mean of 3.6 patterns (range 1-8) was identified per case. Fused microacinar glands (52.9% of cases) and ill defined glands with poorly formed glandular lumina (50.7%) comprised the predominant and most frequently admixed patterns. Also detected were single cells (48.5%), single signet ring cells (34.6%), cribriform glands (31.6%), sheets of cells (22.8%), chains (4.4%), comedonecrosis (2.2%), and hypernephromatoid (0.7%) patterns. GS 8-10 carcinoma was typically extensive, with a mean of 4.6 positive cores (range 1-15) per case. Only two cases (1.5%) had a very small carcinoma focus (1-2 mm), with ill-defined glands with poorly formed lumina and single cell patterns being present in these two cases. Patterns not present in the ISUP report include single file growth, nested, and solid cylinder patterns. The single file pattern, similar to that seen in lobular breast carcinoma, was present, usually focally, in 35.3% of the cases. The small solid nested pattern was detected in 22.8% of the needle biopsy cases. Only one case (0.7% of cases) had solid cylinders.
Conclusions: The results show that patterns of Gleason score 8-10 prostatic adenocarcinoma can be stratified based on their frequency of occurrence in needle biopsy. We characterize the frequency of the ISUP-defined and additional patterns including single file, small nested, and solid cylinder arrangements. For diagnostic recognition purposes it is important to be aware of the frequency of various patterns encountered in Gleason score 8-10 adenocarcinoma, the types of admixtures, and the histomorphological presentation of unusual variants.
Category: Genitourinary (including renal tumors)

Wednesday, March 2, 2011 9:30 AM

Poster Session V # 78, Wednesday Morning

 

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