Generalised Hyperpigmentation Caused by Ectopic Adrenocorticotropic Hormone Syndrome with Recurrent Thymic Neuroendocrine Carcinoma

Ectopic adrenocorticotropic hormone (ACTH) syndrome is a rare cause of generalised hyperpigmentation. The clinical features are due to the excessive ectopic secretion of adenocorticotropin by diverse neuroendocrine or non-endocrine tumours. Here, we describe a rare case of ectopic ACTH syndrome developing from recurring thymic neuroendocrine carcinoma, which first presented as generalised hyperpigmentation.