[822] Expression Patterns of Carbonic Anhydrase IX in Bladder: Non-Neoplastic and Neoplastic Entities

MR Cox, W Winham, M Quick, T Kelly, N Gokden. University of Arkansas for Medical Sciences, Little Rock, AR

Background: Carbonic anhydrase IX (CA9) is a hypoxia-induced protein and is shown to be expressed in some renal cell carcinomas but little is known about its expression patterns in bladder tissue. In this study, we assessed CA9 expression in unremarkable and reactive bladder mucosa, and urothelial neoplasms, and correlated it with tumor grade.
Design: Retrospectively, a total of 98 cases (94 biopsies, 4 transurethral resection of bladder tumors) were selected between 1998-2008 and stained with CA9. The study group consisted of 28 benign bladder mucosae; 7 reactive urothelia; 1 papillary hyperplasia; 3 nonkeratinizing squamous metaplasia; 3 papillomas; 3 inverted papillomas; 13 urothelial carcinoma in situs (UCIS); 5 papillary urothelial neoplasms of low malignant potential (PUNLMP); 15 low grade papillary urothelial carcinomas (LGPUC) (non-invasive); 11 high grade papillary urothelial carcinomas (HGPUC) (5 invasive, 6 non-invasive); 9 invasive urothelial carcinomas (IUC) (8 with lamina propria invasion, 1 with muscularis propria invasion). The extent of cells with membranous/cytoplasmic granular staining was scored semiquantitively as 0 negative, 1+ (1-25% of cells staining, 2+ (26-50%), 3+ (>50%).
Results:

Results of CA9 staining is summarized in table 1.

Histologic diagnosis	Positive staining	Negative	Total
Benign	0 ( 0%)	28 (0%)	28
Reactive urothelium	0 ( 0%)	7 ( 0%)	7
papillary hyperplasia	0 ( 0%)	1 (0%)	1
Squamous metaplasia	0 ( 0%)	3 ( 0%)	3
Papilloma	1 (1+) (33%)	2 ( 67%)	3
Inverted papilloma	1 (1+) ( 33%)	2 (67%)	3
CIS	0 (0%)	13 ( 0%)	13
PUNLMP	3[2(1+);1(2+)] (60%)	2 (40%)	5
LGPUC	7 [6(1+);1(2+)] (47%)	8 (53%)	15
HGPUC	3 [2(1+);1(2+) (27%)	8 (73%)	11
IUC	0 ( 0%)	9 (0%)	9
Total	15 (15%)	83 (85%)	98

CA9 has a sensitivity of 100% and specificity of 73% for papillary urothelial neoplasms. CA9 is not expressed in unremarkable bladder mucosa (p 0.0049), and is positive only in papillary urothelial neoplasms (p 0.0001). In addition, it is potentially a useful marker for LGPUC (p 0.0015) and PUNLMP (p 0.0245). Staining was present mainly in cells lining the superficial layers of the papillary urothelial neoplasms.
Conclusions: CA9 is potentially a useful marker for papillary urothelial neoplasms and in particular for LGPUC and PUNLMP.
Category: Genitourinary (including renal tumors)

Wednesday, March 24, 2010 1:00 PM

Poster Session VI # 144, Wednesday Afternoon