PIGMENTED RENAL-CELL CARCINOMA

A rare case of pigmented renal cell carcinoma is presented. The tumor was yellow, somewhat elastic, and soft with focal gray and tan areas. Microscopically, the tumor was a typical renal cell carcinoma of the c lear-cell type. Tumor cells containing brown pigment in the cytoplasm were scattered throughout the tumor. Ultrastructurally, the electron-d ense granules consistent with the brown pigment noted at the microscop ic level showed a coarse or fine granular matrix with or without homog eneous high electron-dense areas, resembling lipofuscin. However, the nature of the pigment was different from that of lipofuscin by the Mas son-Fontana method after bleaching and rather similar to neuromelanin. The current case is a rare renal cell carcinoma with pigmentation att ributed to abnormally excessive accumulation of neuromelanin pigment.