Pigmented hepatocellular adenoma: report of a case.

Hepatocellular adenoma is a rare, benign neoplasm that is related to the use of contraceptives or androgenic-anabolic steroids. A 51-year-old man with no history of steroid use was found to have a liver tumor. Plain computed tomography showed a high-density tumor that was enhanced in the arterial phase, and the enhancement was prolonged in the delayed phase. Magnetic resonance imaging showed that the tumor was hyperintense on in- and opposed-phase T1-weighted gradient recalled echo images and hyperintense on T1-weighted spin echo images. A partial hepatic resection was performed. A histological examination revealed normal hepatocyte-like tumor cells, composed of abundant dark brown granules of Dubin-Johnson-like pigment, which stained positively for Masson-Fontana stain. The tumor was diagnosed to be a very rare hepatocellular adenoma with the deposition of Dubin-Johnson-like pigment.