Unilateral macronodular adrenal hyperplasia as an unusual cause of Cushing's syndrome--a case study

To appraise clinicians of the problems that may be encountered in the diagnosis and management of Cushing's syndrome, we present a case report of a 20-year old female, who was admitted with a recently developed central obesity, ammenorrhea hirsuitism, proximal myopathy and depression. She was found to have multiple striae, thin skin, elevated blood pressure glycosuria and hyperglycaemia. Morning and mid-night plasma cortisol concentrations revealed elevated levels, with a loss of diurnal variation. There was a failure of the normal suppressibility of cortisol secretion by low doses of dexamethasone, while a significant suppression of plasma cortisol concentration was observed with high doses of dexamethasone. There were no significant abnormalities observed in the pituitary fossa on skull radiograph and on the cranial computerised tomographic scan. After a period of stabilisation, she had a bilateral adrenalectomy done, with a histopathological finding of a left adrenal macronodular hyperplasia, while the right adrenal gland was small and friable. There was an uneventful post-operative period, with a gradual return to normality of most of the presenting complaints. The hyperglycaemia and hypertension got controlled without medications, while her menstrual cycles resumed within three months of bilateral adrenalectomy. This case report illustrates that an adrenal-dependent Cushing's syndrome may mimic a pituitary-dependent one, especially as regards the suppressibility of plasma cortisol secretion by high doses of dexamethasone.