[Cushing's syndrome due to a pulmonary carcinoid].

Cushing paraneoplasic syndrome is a rare cause of hypercorticism. We report a case of 35 year-old man presenting with Cushing's syndrome characterized by severe signs of hypercorticism and hypokalemia. Endocrine investigations were suggestive of an hypercortisolism linked to an ectopic adrenocorticotropic (ACTH) secretion, both at baseline (mean ACTH levels=275 pg/ml, urinary free cortisol excretion=3.898 mmol/24 h) and after pharmacodynamic testing (lack of inhibition of ACTH by dexamethasone). Thoracic tomodensitometric examination revealed a 15 mm tumor corresponding to a neuroendocrine pulmonary carcinoid with positive immunostaining for chromogranin A. Postoperative ACTH measurement was undetectable, plasma cortisol and free urinary cortisol were also decreased after tumor resection suggesting complete tumor removal. This case report illustrates the characteristics of paraneoplasic Cushing syndrome due to ACTH secreting pulmonary neuroendocrine carcinoid.