DIABETES-INSIPIDUS FOR 5 YEARS PRECEDING THE DIAGNOSIS OF HYPOTHALAMIC LANGERHANS CELL HISTIOCYTOSIS

We report a case of an adult male with Langerhans cell histiocytosis ( LCH), in which the hypothalamic involvement went undetected by radiolo gy and who was diagnosed as having central diabetes insipidus for 5 ye ars before the skin lesions and the hypothalamic mass became evident o n a CT scan. The skin lesions spontaneously disappeared but relapsed 1 2 months later. The hypothalamic mass disappeared six months after low dose radiotherapy with persistance of diabetes insipidus and loss of thirst sensation. We did not observe relapse of the hypothalamic mass within the five years of post-radiotherapy follow-up. Despite the fact that patients with LCH may experience spontaneous remissions and exac erbations in their clinical manifestations, the patient's longterm evo lution suggested the mass was cured. We would like to draw the attenti on of clinicians to the necessity of long-term follow-up in patients i nitially diagnosed of idiopathic central diabetes insipidus. Furthermo re, low dose radiotherapy is a successful treatment for LCH-dependent masses in the hypothalamus; however, normalization or regression of CT abnormalities after radiotherapy did not affect the clinical diabetes insipidus status.