Lipid-Rich Variant of Urothelial Carcinoma Presenting as the Dominant Morphology in a Recurrent Tumor After Local Therapy.

BACKGROUND The lipid-rich variant is a rare and aggressive type of urothelial carcinoma (UCa), with less than 40 cases reported in the literature. This variant usually presents as an advanced-stage primary tumor. CASE REPORT We report the case of a 61-year-old man with previous history of T1 high-grade conventional urothelial carcinoma treated with local therapy. The patient later presented with a new 6.5-cm exophytic bladder mass. Histopathological examination revealed a T2 urothelial carcinoma of the lipid-rich variant. Retrospective review of the previous biopsies confirmed conventional high-grade urothelial carcinoma, but scattered rare individual or small clusters of cells that resemble the lipid-rich variant urothelial carcinoma were also noted. CONCLUSIONS The findings in this case suggest that the differential sensitivity of conventional urothelial carcinoma to local therapy may have allowed the lipid-rich variant to predominate in the recurrence. Pathologists should be aware of the lipid-rich variant of urothelial carcinoma. The prognostic significance of rare lipoblast-like cells among predominantly conventional urothelial carcinoma may requires further study.