Ectopic Cortisol-producing Adrenocortical Adenoma Detected by 131I-6β-iodomethyl-norcholesterol Scintigraphy

A 50-year-old man was referred to our department for overt Cushing's syndrome (CS). His plasma cortisol concentrations were 314 μg/L, and his urinary cortisol concentrations were 431 μg/day. The plasma adrenocorticotropic hormone (ACTH) concentration was below the detectable limit. Computed tomography revealed atrophy of both adrenal glands and the presence of a left pararenal tumor. 131I-6β-iodomethyl-norcholesterol scintigraphy showed an intense uptake by the left pararenal tumor. These findings suggested that the left pararenal tumor was ectopic cortisol-producing adrenocortical adenoma. This case serves as a reminder that 131I-6β-iodomethyl-norcholesterol scintigraphy is an effective method for diagnosing ACTH-independent CS in which no adrenal tumor has been found.