Primary tumorous aldosteronism due to a black adrenal adenoma: a light and electron microscopic study.

A case of primary tumorous aldosteronism due to a black adrenal adenoma in a 37-year-old man is reported. Light microscopy showed the tumour to consist predominantly of compact cells containing intracytoplasmic lipofuscin, accompanied by zona fasciculata and intermediate type cells. Electron microscopy identified compact and interface (inner zona fasciculata) type cells, and also demonstrated spironolactone bodies in a compact cell. The morphological appearance of the tumour and adjacent adrenal gland, combined with the clinical and biochemical findings, supports both its secretory function and its classification as a rare variant of the more common non-pigmented aldosteronoma.