Pigmented Granules in Functional Black Adenoma of the Adrenal Gland: A Histochemical and Ultrastructural Study

A black adenoma of the adrenal gland was laparoscopically removed from a 61-year-old Japanese female who had clinical and laboratory findings characteristic of Cushing's syndrome. The tumor consisted of polygonal cells that contained numerous brown pigmented granules of various sizes by routine hematoxylin-eosin staining. The histochemical study showed that the pigment had the characteristics of lipofuscin, not of melanin or neuromelanin. Electron microscopic study revealed tumor cells with two types of pigmented granules. These results show that there might be differences in the lipid metabolism of individual tumor cells in black adenomas of adrenal; which suggests an interesting histogenesis for these granules.