Unusual cause for recurrent Cushing syndrome and its diagnosis by computed tomography and NP-59 radiocholesterol scanning.

Cushing syndrome can recur following an adrenalectomy. One of the primary causes is recurrence of adrenal carcinoma either locally or from metastases. Hyperplasia and hyperfunction of adrenal remnants may also occur if there is pituitary stimulation. We have a patient in whom recurrent Cushing syndrome developed from small nonmalignant deposits of adrenal tissue in the perirenal adipose tissue following adrenalectomy of a benign adenoma. These deposits were identifiable by computed tomography. A false-negative NP-59 iodocholesterol scan was instructive in pointing out some problems in the interpretation of this type of scan for adrenal tissue.