Black (or brown) adrenal cortical adenoma: its characteristic features on computed tomography and endocrine data.

Seventeen patients with adrenal adenoma causing Cushing's syndrome, eight patients with Cushing's disease due to hypersecretion of ACTH, and five patients with primary aldosteronism due to an aldosteronoma were studied for their computed tomographic (CT) patterns, hormonal profiles, and macroscopic and microscopic findings of the adrenal gland. Black (or brown) adrenal adenomas were found in 71% of the patients with Cushing's syndrome, but not in patients with aldosteronoma. The adrenal tissue of patients with Cushing's disease was predominantly yellow. The number of compact cells was larger in black or brown adenomas than in yellow tumors or hyperplastic adrenal tissue. In patients with Cushing's syndrome, urinary excretion of 17-ketosteroids (17-KS) and serum aldosterone concentrations were lower in those with black or brown adenomas than in those with yellow adenomas (P less than 0.05). Patients with Cushing's disease had even higher 17-KS and serum aldosterone levels. No difference was found in serum cortisol concentrations and dexamethasone suppressibility in two types of adenomas causing Cushing's syndrome. Visual estimation of radiological density of the adrenal tissue relative to the kidney on CT scan and quantitative measurement of it by CT number revealed a difference between the two types of adrenal tumors causing Cushing's syndrome. Adrenal tumors with decreased density on CT scan were yellow adenomas with predominantly clear cells, and those with equal or increased density were black or brown adenomas with predominantly compact cells. All aldosteronomas had decreased density and consisted of clear cells. It is suggested that black or brown adenomas of the adrenal gland have higher radiological density and accompanying lower serum aldosterone and urinary 17-KS levels than ordinary yellow tumors. The abundance of compact cells may have some significance for the development of this particular type of adrenal tumor.