[1066] GATA3 Expression in Nested, Micropapillary, and Plasmacytoid Urothelial Carcinomas

Joshua Warrick, Nallasivam Palanisamy, Javed Siddiqui, Rohit Mehra, Angela Wu, Scott Tomlins, L Priya Kunju. University of Michigan, Ann Arbor, MI

Background: GATA3 has been previously shown to demonstrate high levels of expression in breast carcinoma and urothelial carcinoma (UC). UCs with nested, micropapillary, and plasmacytoid features are associated with poor outcome. To our knowledge, GATA3 expression has not been evaluated in nested or micropapillary UC. The purpose of this project was to evaluate GATA3 expression in these histologic variants of UC by immunohistochemistry (IHC). A benign mimic of nested UC (proliferative cystitis) and benign urothelium were also evaluated for comparison.
Design: GATA3 IHC (sc-268; Santa Cruz Biotech; Santa Cruz, CA) was performed on nested (n=9), micropapillary (n=10), and plasmacytoid (n=7) UC cases retrieved from our archives (22 cases) or tissue microarrays (TMA; 3 micropapillary, 1 plasmacytoid). Benign bladder urothelium (n=20, from TMA) and proliferative cystitis (n=3) were also evaluated. Nuclear staining intensity (graded as negative, weak, moderate, or strong; moderate and strong considered positive) and percentage of cells demonstrating GATA3 expression were assessed.
Results: GATA3 positivity was noted in 89% (8/9) of nested, 100% (10/10) of micropapillary, and 57% (4/7) of plasmacytoid UCs. Strong nuclear staining was seen in the majority of micropapillary (9/10) and nested (5/9) UCs. All positive plasmacytoid UCs showed strong nuclear staining. Micropapillary UCs showed diffuse GATA3 expression in the majority of cases (9/10 showed ≥50% cells staining), while plasmacytoid UCs (2/4 positive cases showed ≤50% cells staining) and nested UCs (5/9 cases showed ≤50% cell staining) tended to show focal expression. GATA3 was positive in most benign urothelium (16/20 cases; all moderate to strong) and all proliferative cystitis cases (3/3; all strong). Staining tended to be diffuse in benign urothelium (11/16 positive cases showed >50% cells staining) and proliferative cystitis (2/3 showed >50% of cells staining).
Conclusions: GATA3 expression as detected by IHC is present in the majority of nested, micropapillary, and plasmacytoid UCs. These findings corroborate one previous report regarding the expression of GATA3 in the plasmacytoid variant of UC. Our current study suggests high level of GATA3 expression in nested and micropapillary UCs as well. GATA3 may be useful for accurately classifying the primary site of a micropapillary carcinoma as bladder if metastatic breast carcinoma can be excluded. Benign urothelium and proliferative cystitis both demonstrate strong expression of GATA3 in the majority of cases, making GATA3 unsuitable for differentiating these from the nested pattern of UC.
Category: Genitourinary (including renal tumors)

Tuesday, March 5, 2013 9:30 AM

Poster Session III # 102, Tuesday Morning


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