A patient with diabetes insipidus and periorbital swellings; Erdheim-Chester disease.

Erdheim-Chester disease is a rare multisystem disease in which a progressive xanthogranulomatous infiltration of several tissues can be seen. We describe a woman, known to have diabetes insipidus for ten years, with periorbital, retroperitoneal, mediastinal, axillar and inguinal involvement. On histological examination a granulomatous infiltration of fatty tissue and striated muscle was seen, consisting of Touton giant cells, histiocytes with foamy cytoplasm and lymphocytes. Immunohistochemical staining with CD-1a and S-100 was negative and on electron microscopy no Langerhans granules were seen. These findings led to the diagnosis of Erdheim-Chester disease. She had a good response on steroids. Because of some similar clinical features of Langerhans cell histiocytosis and Erdheim-Chester disease, a histiocyte disorder seems the most probable cause.