A black hepatocellular carcinoma with Dubin-Johnson-like pigment and Mallory bodies: a histochemical and ultrastructural study.

A hepatocellular carcinoma which was predominately black was surgically excised from a noncirrhotic, asymptomatic 62-year-old white man. Brown-black, pigment granules, found only in the tumor cells, were histochemically and ultrastructurally identical to the hepatocellular pigment found in Dubin-Johnson syndrome. The latter pigment is thought to accumulate as a consequence of a genetically determined abnormality in the excretion of catecholamines and related substances. It is postulated that the pigment formation in this tumor developed via a similar, though epigenetic, mechanism. This occurrence has not been previously described. Unusual PAS-negative, globular cytoplasmic inclusions were also found in the tumor cells and these proved to be Mallory bodies by electron microscopy.