Urothelial Carcinoma with shadow cell, lipid cell and sebaceous (skin adnexal) differentiation: Clinicopathological and immunohistochemical study of 10 cases.

We discuss the histological and immunohistochemical features of 6 cases of urothelial carcinomas of lipid cell variant and 4 cases with shadow cell differentiation, one of which showed additionally sebaceous differentiation, one of which shows additional sebaceous differentiation, from our archive cases from the last 15 years. Conventional urothelial carcinoma (UC) was seen in all lipid cell variant cases, and micropapillary carcinoma was seen in 3. The ratio of the lipid cell component was between 10% and 40% in these 6 cases. Typical histologic features of the lipid cell variant include lipoblast-like cells with a notched nuclear appearance, abundant vacuoles, an eccentric nucleus, and pagetoid spread in some areas. GATA3 and pancytokeratin AE1/AE3 immunohistochemical staining were positive in all cases. Adipophilin was positive in various degrees in 5 of the 6 lipid cell variant cases but was also positive in the case with sebaceous differentiation. α-methylacyl-CoA racemase was positive in the lipid cell areas and negative or focal weakly positive in the conventional UC areas in 4 of the 6 cases. Vimentin, S-100 protein, and PAX8 were negative in the lipid cell component. Follow-up information was available for all cases with follow-up ranging from 6 to 84 months (mean, 34 months). Four patients died of the disease. One pT4 patient who had been followed up for 6 months lives with the disease, whereas another is disease free. In conclusion, the lipid cell variant is a rare UC variant that usually presents at an advanced stage, and tumor cells are histologically similar to lipoblasts, resemble sebaceous differentiation, and show positive immunohistochemical staining with adipophilin.