Urothelial carcinoma of the bladder, lipid cell variant: A case report and literature review.

Lipid cell variant of urethral carcinoma (UC) is a rare tumor and has been clinicopathologically poorly understood. A nodular tumor was detected in the bladder of an 87-year-old man with asymptomatic gross hematuria; the tumor was transurethrally resected. The patient was pathologically diagnosed with high-grade UC, lipid cell variant. The tumor cells, similar to lipoblasts, commonly contained cytoplasmic vacuoles. Immunohistochemically, the tumor cells were positive for epithelial markers such as CK7, 20, EMA, CAM5.2, and 34betaE12. However, they were negative for vimentin and S100. Moreover, focal positivity for adipophilin was detected in the cytoplasm, but not in the vacuoles. Based on these observations, we believe that the study patient could have lipid-producing UC.