Choroidal mass as the first presentation of Erdheim-Chester disease.

To describe a choroidal mass that proved to be histiocytic choroidal infiltration in Erdheim-Chester disease. A 54-years-old Caucasian male presented to our Retina Clinic with a suspect of choroidal melanoma in the left eye. Dilated fundus exam of the left eye showed a yellow-grey lesion along the inferior arcade, with sub-retinal fluid clinically visible. Enhanced depth imaging-OCT (EDI-OCT) showed a dome-shaped choroidal lesion with hyperreflective exudation present between the inner retina and the retinal pigment epithelium (RPE). On fundus autofluorescence the lesion appeared to have a diffuse speckled hyper-autofluorescent pattern secondary to the exudative subretinal material. On ultrasound, the lesion appeared hyper-echoic and dome-shaped, with a baseline thickness of 6.13 mm. Indocyanine green angiography (ICGA) was performed and showed hypocyanescence of the lesion from the early phases that persisted through the whole exam. Chest CT with contrast showed an abnormal, non-calcific, eccentric thickening of segments of the aorta ("coated aorta") and PET an abnormally strong labeling of the distal ends of the long bones. An additional proximal tibial biopsy was performed to confirm the diagnosis on histology of Erdheim-Chester disease and the patient was started on oral prednisone. The choroidal mass progressively shrunk and the subretinal exudative material on top partially reabsorbed. Intraocular involvement in Erdheim-Chester disease is extremely rare but as a result of recent better awareness the number of new diagnosis is increasing. Erdheim-Chester disease should be considered in the differential of every choroidal mass.