[868] Utility of CD34 and CD31 in the Distinction between Invasive Micropapillary Urothelial Carcinoma and Invasive High Grade Urothelial Carcinoma with or without Pseudo-Micropapillary Features.

Scott R Lauer, Adeboye O Osunkoya. Emory University School of Medicine, Atlanta, GA

Background: Micropapillary urothelial carcinoma is an aggressive variant of urothelial carcinoma. The distinction between this entity and usual type urothelial carcinoma or urothelial carcinoma with pseudo-micropapillary features has become increasingly important in view of therapeutic and prognostic implications. Unfortunately, recent studies have shown some degree of lack of interobserver reproducibility even amongst urologic pathologists. To date, only very few immunohistochemical stains such as MUC1 which is not readily available in most academic institutions or private laboratories have been proposed to aid in the distinction between micropapillary urothelial carcinoma and usual type urothelial carcinoma or urothelial carcinoma with pseudo-micropapillary features. In this study, we demonstrate the utility of CD34 and CD31 in this regard.
Design: A search was made through the surgical and consultation files at our institution for cases of micropapillary urothelial carcinoma. A control group of usual type urothelial carcinoma and urothelial carcinoma with pseudo-micropapillary features was also identified. A representative slide/block of each case was selected and immunohistochemical stains for CD34 and CD31 were performed. The immunohistochemical stains were reviewed for the presence of positive staining within the center of the tumor papillae or invasive nests, and the results were documented. Areas of angiolymphatic invasion were excluded.
Results: 23 cases with a diagnosis of micropapillary urothelial carcinoma of the bladder with available tissue blocks were identified from 2002 to 2010. 30 cases of usual type urothelial carcinoma and urothelial carcinoma with pseudo-micropapillary features were selected. 23/23 cases (100%) of micropapillary urothelial carcinoma lacked expression of CD34 and CD31 within the center of invasive tumor micropapillae. In contrast, 30/30 cases (100%) of usual type urothelial carcinoma and urothelial carcinoma with pseudo-micropapillary features demonstrated positive expression of CD34 and CD31 within the center of invasive tumor papillae.
Conclusions: To the best of our knowledge, our study is the first to examine the utility of readily available markers CD34 and CD31 in the distinction between invasive micropapillary urothelial carcinoma and invasive usual type urothelial carcinoma or urothelial carcinoma with pseudo-micropapillary features. CD34 and CD31 may aid in the distinction between these entities when confronted with equivocal cases.
Category: Genitourinary (including renal tumors)

Monday, February 28, 2011 9:30 AM

Poster Session I Stowell-Orbison/Surgical Pathology/Autopsy Awards Poster Session # 120, Monday Morning

 

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