A CASE OF PITUITARY DEPENDENT CUSHING'S DISEASE WITH CLINICAL AND BIOCHEMICAL FEATURES OF THE ECTOPIC ACTH SYNDROME

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Abstract
SUMMARY: A case of atypical pituitary dependent Cushing's disease is reported. The patient presented with clinical symptoms similar to those of the ectopic ACTH syndrome; notably a marked hypokalaemic alkalosis, widely fluctuating plasma cortisol levels, greatly elevated plasma ACTH levels, and failure to suppress both plasma cortisol and ACTH levels following high dose oral dexamethasone. However, a large aggressive pituitary tumour was detected by skull X‐ray and computed tomography. Removal of the pituitary tumour led to full remission of the patient's Cushing's syndrome. Pro‐opiomelanocortin (POMC) related peptides in the plasma and tumour tissue extract of this patient have been characterized by gel‐filtration and Concanavalin‐A Sepharose affinity chromatography, indicating processing of POMC in a manner more usually associated with ectopic tumours.