Central diabetes insipidus and Cushing's syndrome due to ectopic ACTH production by disseminated small cell lung cancer: a case report.

The present case report describes the rare clinical presentation of diabetes insipidus in a patient with an ectopic ACTH syndrome (morning plasma cortisol 1.10 mumol/l, morning plasma ACTH 322 ng/l) due to disseminated small cell lung cancer including a metastasis in the posterior pituitary. The patient was treated by combination chemotherapy and at the same time received octreotide to control hypercortisolism and desmopressin (DDAVP) to control polyuria. Partial tumour remission was achieved resulting in decreased cortisol production and disappearance of the diabetes insipidus. Medical treatment could be discontinued. Several months later tumour regrowth occurred, with recurrence of hypercortisolism (mean morning plasma cortisol 0.74 mumol/l, mean morning plasma ACTH 112 ng/l) but without diabetes insipidus. Early treatment of hypercortisolism in patients with an ectopic ACTH syndrome and disseminated small cell lung cancer may prolong survival and improve the quality of life.