[928] Primary Versus Secondary Bladder Adenocarcinoma: A Diagnostic Challenge.

Somak Roy, Anil V Parwani. UPMC, Pittsburgh, PA

Background: Primary bladder adenocarcinoma (PBA) is a rare tumor characterized by malignant glandular proliferation with varying degrees of differentiation. These tumors are difficult to distinguish from colonic adenocarcinomas based on morphological features, especially on limited specimens. There is limited data available about the role of immunohistochemical (IHC) markers in distinguishing PBA from secondary bladder adenocarcinomas (SBA). In this study we have attempted to analyze a set of immunohistochemical markers and in distinguishing the two groups.
Design: A total of nine cases of bladder adenocarcinomas (5 PBA & 4 SBA) were studied. The control group included 5 cases each of urothelial carcinoma (UC) and colonic adenocarcinoma (CA). Morphological features were assessed on Hematoxylin and eosin stained sections. IHC by Streptavidin-biotin method using DAB chromogen was performed for cytokeratin 7 (CK7), cytokeratin 20 (CK20), beta-catenin, E-Cadherin, Villin and CDX-2. Cytoplasmic/membranous (CM) versus nuclear staining was assessed for beta-catenin and cytoplasmic and/or membranous staining was assessed for the other immunomarkers. Florescence in-situ hybridization (FISH) studies targeting chromosomes 3, 7, 9 and 17 are underway to further investigate possible differences between the tumor types.
Results: Nine cases of bladder adenocarcinomas included 5 males and 4 females in the age range of 25-87 years. All cases of PBA were characterized by infiltrating intestinal type malignant gland. Two tumors had mucinous features and one had signet ring cells. Three of 4 SBA were metastatic from the GI tract and one represented a divergent glandular differentiation in an UC. IHC staining for beta-catenin demonstrated CM staining in all PBA and additional strong nuclear staining in 3 of 4 SBA. The control cases of CA showed strong nuclear as well as CM expression of beta-catenin in 4 of 5 cases. No difference in staining pattern was observed with CDX2, villin, E-Cadherin and CK20. CK7 expression was restricted to benign and malignant urothelium and only one case of PBA.
Conclusions: In summary, the above findings suggest that beta-catenin can be used in conjunction with morphological and clinical information to aid in distinguishing PBA from SBA. This may help support the hypothesis that the dysregulation in the Wnt signaling pathway due to beta-catenin is operative in SBA and CA, unlike PBA. Although CK7 may help in distinguishing colonic from urothelial tumors, it cannot differentiate between glandular neoplasms of both organs. CK20, CDX2, Villin and E-cadherin do not appear to be of diagnostic use in this scenario.
Category: Genitourinary (including renal tumors)

Tuesday, March 1, 2011 9:30 AM

Poster Session III # 195, Tuesday Morning


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