[840] Identification of Gleason Pattern 5 on Prostatic Needle Core Biopsy: Frequency of Underdiagnosis and Morphologic Analysis

DA Fajardo, TK Lee, JS Miller, H Miyatmoto, JI Epstein. Johns Hopkins Medical Institution, Baltimore, MD

Background: It has been our anectdotal experience that pathologists underdiagnose Gleason pattern 5 prostate cancer, possibly because of hesitance to assign a grade which has such adverse prognostic implications. The current study assesses the accuracy of grading of Gleason pattern 5 and potential factors contributing to undergrading.
Design: From the consult service of one of the authors, we identified 59 consecutive needle biopsy cases comprising 138 parts that upon review were graded as having Gleason pattern 5. All cases were reported as the final diagnosis by the outside pathologist. They were sent for 2nd opinion by clinicians or patients and not because the pathologist was seeking a 2nd opinion.
Results: Upon review, the final Gleason score was increased in 101/138 (73.2%), decreased 5/137 (3.6%), and remained unchanged in 32/138 (23.2%). Gleason pattern 5 was correctly identified by the outside pathologist in 71/138 parts (51.4%). The architectural patterns of pattern 5 were: single cells (n=104, 75.3%), solid (n=69, 50%), cords (n=62, 44.9%), and comedonecrosis (n=3, 2.2%). In the 1st column of the table is the total number of cases with each Gleason score. The 2nd column is the number of cases undergraded for each Gleason score. The next 4 columns show the number of undergraded cases for each pattern. For example, with Gleason 4+5=9, of the 18 cases primarily composed of single cells, 14 were undergraded.

Undergrading of Pattern 5: By Morphology

Grade	Total Cases	Underdiagnosis	Mostly Single Cells	Mostly Solid	Mostly Cords	Mostly Comedo
3+5=8	10/138 (7.2%)	8/10 (80%)	3/4 (75%)	2/3 (67%)	3/3 (100%)
4+5=9	56/138 (40.6%)	43/56 (76.8%)	14/18 (78%)	17/23 (74%)	10/13 (77%)	2/2 (100%)
Primary 5	72/138 (52.2%)	15/72 (20.8%)	9/30 (30%)	2/30 (7%)	4/15 (27%)

Conclusions: Pattern 5 was missed in 48.6% of the prostate needle core biopsies. It is most often missed when it is not the primary pattern. The most commonly present Gleason pattern 5 architectural type was single cells and the least common was comedonecrosis. None of the architectural patterns appear to be incorrectly identified more than another. Most accurate grading was when the primary pattern was 5 and composed mostly of solid sheets. Due to the important prognostic and therapeutic implications of Gleason pattern 5, pathologists must be attuned to its varied patterns and that it often may represent a secondary component of the carcinoma.
Category: Genitourinary (including renal tumors)

Monday, March 22, 2010 1:45 PM

Platform Session: Section A, Monday Afternoon