[1071] CD44 Full-Thickness Immunoreactivity Is More Sensitive Than CK5/6 for the Diagnosis of Flat Urothelial Lesions with Atypia

Wendong Yu, Saleem A Umar, Saba Yasir, Merce Jorda. University of Miami Miller School of Medicine, Jackson Memorial Hospital, Sylvester Comprehensive Cancer Center, Miami, FL

Background: Flat urothelial lesions with atypia can pose a diagnostic dilemma when attempting to make the distinction between reactive urothelial atypia (RUA) and carcinoma in situ (CIS). A recent study suggested that CK5/6 may be a useful biomarker to help in this differential diagnosis. The aim of this study is to determine the diagnostic utility of CK5/6 in comparison to CD44 immunostain in the evaluation of flat urothelial lesions with atypia, since both immunostains demonstrate similar immunoreactive patterns.
Design: Thirty-seven transurethral resection of bladder (TURB) biopsies were evaluated. Twenty-eight (76%) cases comprised RUA with benign clinical follow-up and 9 (24%) CIS cases with classic histomorphologic features. All cases were evaluated by immunohistochemistry for CK5/6 (DAKO, RTU) and CD44 (DAKO, 1:25) using the LSAB method. Intensity and staining patterns were determined for each marker. Sensitivity and specificity for the diagnosis of RUA was determined.
Results: Full-thickness staining for CK5/6 was observed in 20 RUA cases. Negative or weak basal staining for CK5/6 was observed in 8 RUA cases and in all 9 CIS cases. Full-thickness staining for CD44 was observed in all 28 RUA cases and in 1 case of CIS. Negative or weak basal staining for CD44 was observed in 8 CIS cases. Sensitivity and specificity for the diagnosis of RUA were 71% and 100% for CK5/6 immunostain, and 100% and 89% for CD44, respectively.
Conclusions: Full-thickness staining for CD44 is more sensitive than full-thickness staining for CK5/6 for the diagnosis of RUA. CK5/6 does not add diagnostic value in this setting, and therefore should not be used as a substitute for CD44 in the traditional triple stain panel (CD44, CK20 and p53) employed in the differential diagnoses of flat urothelial lesions with atypia.
Category: Genitourinary (including renal tumors)

Tuesday, March 20, 2012 1:00 PM

Poster Session IV # 79, Tuesday Afternoon

 

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