Erdheim-Chester disease: a bilateral orbital mass as an indication of systemic disease.

A case of bilateral orbital mass and xanthelasma of the eyelids is presented. Histology confirmed it to be a form of histiocytosis, possibly an Erdheim-Chester disease. This was further confirmed by the presence of a retroperitoneal mass and hydronephrosis, which resolved with treatment. A review of the literature on and pathological features of this rare fatal disease is presented.