A syndrome of diabetes insipidus followed by progressive spastic cerebellar ataxia is reported in four boys from the Departments of Neurology, Pediatrics and Psychiatry, UCLA School of Medicine, Los Angeles, CA. In two patients central nervous system histiocytosis was detected. CT scan showed bilateral calcification of the cerebellar dentate nuclei and multiple hypodense areas in the skull; a biopsy confirmed the diagnosis of histiocytosis. A trial of Prednisone was beneficial. 
COMMENT. Each of these patients developed idiopathic central diabetes insipidus between the ages of two and six years and all responded to intranasal Desmopressin. Spastic cerebellar ataxia developed eight to ten years later. Histiocytosis accounts for 8-16% of cases of diabetes insipidus in children. Patients with this syndrome may benefit from treatment with corticosteroids.