Functioning "black adenoma" of the adrenal gland with emphasis on ultrastructural studies.

An account is given in this paper of functional black adenoma of the adrenal cortex. Autonomous hormone secretion of the tumour was confirmed by pre- and postoperative biochemical tests. Electron microscopy revealed two types of pigment granules. Mitochondria showed severe impairment. A relationship was assumed to exist between mitochondrial alterations and accumulation of lipoid-containing pigment because of the important role of mitochondria in lipid metabolism. Abnormal collagen fibrils were found in the cytoplasm of tumour cells. Comparison of the presented black adenoma with two nonpigmented adrenal adenomas showed the ultrastructure of black-adenoma cells to be similar to the compact cells of "yellow" cortical adenomas. However, the latter contained normal mitochondria and one type of pigment granules. Adrenal black adenoma thus can be regarded as a pathological entity.