ACTH and CRF-producing bronchial carcinoid associated with Cushing's syndrome

A young female patient, with clinical and biochemical manifestations of severe hypercorticism and with the presence of a pituitary adenoma shown by computerized tomography, was thought to have Cushing's syndrome of hypophysial origin. However, the surgically-removed pituitary adenoma contained no ACTH, by immunocytology, and hypercorticism persisted after transsphenoidal adenomectomy. The patient died and autopsy demonstrated an ACTH and corticotrophin releasing factor (CRF)-containing bronchial carcinoid. It can be concluded that bronchial carcinoids can produce ACTH and CRF and can mimic the clinical and biochemical manifestations of pituitary Cushing's syndrome. Thus, the localization of the primary site of hypercorticism can be extremely difficult in patients who have an insidious, occult extrapituitary tumour. Further work is required to establish whether CRF plays a role in the causation of Cushing's syndrome and whether the simultaneous secretion of this peptide can modify the clinical and biochemical manifestations of the ectopic ACTH syndrome.