Positron emission tomography/computed tomography of a rare xanthogranulomatous process: Erdheim-Chester disease.

Erdheim-Chester disease (ECD) is a disseminated xanthogranulomatous infiltrative disease of unknown etiology due to infiltration of different organs and bones by foamy histiocytes. A 37-year-old male with cerebral and periorbital lesions was diagnosed with this rare disease and was evaluated with magnetic resonance imaging (MRI) and 2-deoxy-2-[(18)F]fluoro-D-glucose (FDG) with positron emission tomography/computed tomography (PET/CT) imaging at baseline and following therapy. FDG-PET imaging allowed accurate evaluation of the extent of the disease at baseline, as well as assessment of response to therapy.