Ultrastructure of pigment in adrenocortical pigmented adenomas of Cushing's syndrome and in non-functioning pigmented nodules with respect to tissue steroid analyses.

Ultrastructural and morphometrical analysis of brown pigment in pigmented (black) and non-pigmented adrenocortical adenomas of Cushing's syndrome and non-functioning pigmented adrenocortical nodules was performed in reference to tissue concentrations and in vitro production of steroids by the adenoma tissue. Pigment in pigmented adenomas was of membrane-bound lysosomal nature, while that of pigmented nodules contained membrane-unbound droplets of lipoid character. The morphometrical study showed little difference among individual adenomas. There was no difference between pigmented and non-pigmented adenomas in the amount of production and tissue concentrations of steroids. The steroid concentrations in a pigmented nodule were lower than those in an adenoma of Cushing's syndrome, but not significantly. Discussion is focused on the difference of pigment of lysosomal nature and of lipoid peroxidation.