Human epidermal growth factor receptor 2 expression in micropapillary urothelial carcinoma of the bladder: an analysis of 27 cases

The significance of human epidermal growth factor receptor 2 (HER2) overexpression in breast cancer is well established. However, only a few large studies have analyzed HER2 expression in invasive high-grade urothelial carcinoma (UCA). In this study, we sought to analyze the expression of HER2 in a large cohort of micropapillary UCA. A search was performed through our Urologic Pathology files and expert consult files of the senior author for cases of micropapillary UCA of the bladder. Twenty-seven cases were identified. The mean patient age was 68 years (range: 39-87 years). There were 26 male patients and 1 female patient. Twenty of 27 (74%) cases were positive for HER2. Eleven of 15 (73%) cases with angiolymphatic invasion were positive for HER2. Seven of 10 (70%) cases that developed metastasis were positive for HER2. Six of 11 (54%) cases with pT3 disease were positive for HER2, 8/10 (80%) cases with pT2 disease were positive for HER2, 5/5 (100%) cases with pT1 disease were positive for HER2, and the only case with pTa disease was positive for HER2. In our cohort, a significant number of patients with angiolymphatic invasion also had HER2 overexpression. Interestingly, although the majority of cases with advanced disease also demonstrated positive HER2 expression, it was more predominant in cases with less advanced disease. It is therefore highly conceivable that both patients with early or advanced micropapillary UCA of the bladder, including those with angiolymphatic invasion, may benefit from trastuzumab and other related therapeutic agents. (C) 2016 Elsevier Inc. All rights reserved.