Adrenal insufficiency. A rare initial sign of metastatic colon carcinoma

A 75-year-old woman evaluated for "drop attacks" 3 years after anterior resection for colo-rectal cancer developed hyponatremia associated with a morning cortisol of 5.7 micrograms/dl, a plasma adrenocorticotropic hormone level of 319 pg/ml, and an inadequate response to cosyntropin. Computed tomography scan demonstrated bilateral adrenal masses. Fine needle aspiration biopsy of the adrenals revealed adenocarcinoma, histologically similar to her previous colon carcinoma. Addison's disease secondary to isolated colon cancer metastases to the adrenals is rare. Our report represents the first antemortem histologically confirmed diagnosis of this entity. A review of the available literature is presented.