Syndrome of inappropriate secretion of antidiuretic hormone in a patient affected by metastatic melanoma.

The syndrome of inappropriate secretion of antidiuretic hormone (SIADH) is characterized by hyponatraemia due to water retention resulting from the persistent release of antidiuretic hormone (vasopressin). It may occur in a variety of malignant and non-malignant conditions, in particular in association with oat cell carcinoma, pulmonary and cerebral diseases. We report the case of a male patient affected by melanoma of the right temporal region with brain metastasis who developed acute headache, drowsiness, nausea, vomiting and pathological reflexes. Clinical and laboratory investigations led us to the diagnosis of SIADH. Restriction of fluid intake obtained a good clinical improvement with normalization of laboratory alterations; after 2 months the patient experienced a new episode of SIADH which was promptly treated. As melanoma has been occasionally observed in association with SIADH it should be included in the list of tumours that can cause this particular syndrome.