Expression of epithelial-Mesenchymal transition related markers in Plasmacytoid Urothelial carcinoma of the urinary bladder

Background Plasmacytoid urothelial carcinoma (PUC) of the urinary bladder is a variant of urothelial carcinoma that carries a poor prognosis. The epithelial-mesenchymal transition (EMT) has been demonstrated to contribute to tumor progression. As the cause of the increased aggressiveness of PUC is unknown, we investigated PUC and EMT-related marker expression. Methods A total of 633 bladder carcinoma cases diagnosed from 2006 to 2015 at the Nippon Medical School Hospital were analyzed. Twelve patients were found to have plasmacytoid histology and diagnosed with PUC. Slides were evaluated for percentage of plasmacytoid variant, and stained for E-cadherin, N-cadherin, Vimentin, Fibronectin and Snail expression. Results The incidence of PUC was 1.9% (12/633). The median patient age at diagnosis was 71 years (range, 60–80 years) and the male-female ratio was 11:1. All but three patients had stage T2b or higher. The median overall survival was 10 months. In 10/12 cases, Snail and N-cadherin were positive. Vimentin was positive in 9/12 cases. Fibronectin was positive in 8/12 cases. While E-cadherin was negative in 10/12 cases. Nine cases showed > 10% plasmacytoid component. Eight of the nine patients (88.9%) with > 10% plasmacytoid component died. Conclusions The results indicate that PUC may induce EMT and may be associated with high invasion.