Ectopic Cushing's syndrome: Experience from a tertiary care centre

Background & objectives: Ectopic secretion of adrenocorticotropic hormone (ACTH) is rare, contributing to 10 per cent cases of endogenous Cushing's syndrome. We describe our experience of about two decades of patients with ectopic Cushing's syndrome (ECS) seen at a tertiary care centre from north India. Methods: Records of patients with ECS from 1985 to 2006 were retrospectively reviewed that included the presenting manifestations, clinical symptoms and signs, biochemical investigations including plasma cortisol, ACTH and high dose dexamethasone suppression test (HDDST), imaging modalities to localize the non pituitary source of ACTH production, management and follow up of these patients. Results: The study group included 12 patients (7 men) with mean (+/-SD) age at presentation 27.6 +/- 9.5 yr (range 13 to 48 yr) and the mean lag period between onset of symptoms and the diagnosis was 18.3 +/- 12.9 months with a range of 3 to 48 months. The weight loss (41.7%) followed by hyperpigmentation (25%) and infections (16.7%) were the common presenting manifestations. Cuticular atrophy (100%), hypertension (100%), bruise (92%) and proximal myopathy (83%) were the commonest signs. Plasma cortisol at 0800 h was 1267.3 +/- 483.3 nmol/l and at 2200 h was 1214.9 +/- 442.6 nmol/l indicating loss of circadian rhythm. The mean plasma ACTH was 221.1 +/- 55.9 (range 21.7 to 950 pg/ml). All but 2 patients had non-suppressibility of 0800 h plasma cortisol with HDDST. Five patients had thymic carcinoid, 3 had bronchial and one each had islet, hepatic and gut carcinoid and one had medullary thyroid carcinoma as a cause of ectopic ACTH secretion. The mean duration of follow up of these patients was 42.6 months and only two could sustain cure while remaining had either residual or recurrence. Interpretation & conclusion: Ectopic Cushing's syndrome is a rare disease with varied manifestations and associated with increased morbidity and mortality. It presents with clinical features quite similar to classical Cushing's. Surgery with removal of primary tumour was found to be treatment. of choice.