Pitfalls in the Diagnosis of Ectopic Adrenocorticotropic Hormone Syndrome: A Case Report

Abstract

Ectopic production of adrenocorticotropic hormone by carcinoid tumours is uncommon and covert and occult presentations often hamper its diagnosis. A 27-year-old man was admitted with multiple vertebral bodies collapse related to osteoporosis along with other clinical features consistent with Cushing’s syndrome. Both basal and dynamic laboratory evaluation suggested adrenocorticotropic-dependent Cushing’s syndrome diagnosis, specifically ectopic adrenocorticotropic syndrome. Laboratory testing also showed high serum levels of chromogranin A and urinary 5-hydroxyindoleacetic acid. Pituitary and thoracic-abdominal-pelvic imaging proved to be normal, including the octreoscan. To reduce cortisol levels, and before resorting to adrenalectomy, metyrapone was prescribed but eucortisolism was not achieved. Octreotide therapy reduced plasma adrenocorticotropic hormone and cortisoluria to half although the octreoscan had been negative. As no primitive tumour had been detected, the patient underwent bilateral adrenalectomy. Two years and a half after the diagnosis, an octreoscan detected a lung tumour, which was resected. Pathological analysis revealed an atypical carcinoid tumour and immunohistochemistry was positive for adrenocorticotropic hormone but negative for corticotropin-releasing hormone and chromogranin A. Clinical and biochemical resolution of Cushing’ syndrome followed but chromogranin A levels remained above normal. This case highlights both that, although rare, an exuberant osteoporosis can be the initial presentation of ectopic adrenocorticotropic hormone syndrome and high chromogranin A levels may have other origin than direct tumour production. It also raises the question of prescribing somatostatin agonists in patients whose octreoscan is negative as small tumours may produce false negative results. Moreover, the reduction of hypercortisolism before surgery may improve the surgical outcome and with bilateral adrenalectomy may contribute to the primary tumour growth and detection. J Endocrinol Metab. 2013;3(1-2):29-37 doi: https://doi.org/10.4021/jem145w