GANGLIONEUROBLASTOMA OF THE THYMUS - AN ADULT CASE WITH THE SYNDROME OF INAPPROPRIATE SECRETION OF ANTIDIURETIC-HORMONE

A 61-year-old woman was admitted to the hospital because of general fa tigue. Laboratory examinations showed hyponatremia, plasma hypo-osmola rity, and inappropriate increased concentration of the plasma antidiur etic hormone (ADH) in the presence of concentrated urine. Magnetic res onance imaging revealed a mass lesion in the anterior mediastinum. An extended thymectomy was performed under the diagnosis of thymoma with the syndrome of inappropriate secretion of antidiuretic hormone (SIADH ). Histologically the tumor was located in the thymic tissue and was d iagnosed as ganglioneuroblastoma. Immunohistochemical studies showed t he existence of ADH in the tumor cells. To the knowledge of the author s, this is the first case of ganglioneuroblastoma of the thymus with S IADH. (C) 1996 by W.B. Saunders Company