Cushing's syndrome with intermittent ectopic ACTH production.

A case of ectopic ACTH syndrome with intermittent secretion in a 72-yr-old woman is described. Plasma and urinary cortisol levels were obtained at frequent intervals for a period of more than 10 months and varied erratically from the normal range to extremely high values. Nonsuppression by high doses of dexamethasone was documented during a period of hypersecretion. Normal circadian rhythmicity and normal responses to hypoglycemia were observed during an interval of dormance of the ectopic secretion. Hypokalemia did not develop. These findings, together with the occult nature of the primary tumor, resulted in unusual diagnostic difficulties. Liver masses were detected by echography and CT scan. Pathological examination of liver biopsies suggested a neuroendocrine tumor of foregut origin. While a multicentric primary apudoma secreting ACTH was a putative diagnosis, detailed and extensive microscopic post-mortem studies revealed a more likely primary tumor site in the pancreatic tail.