Beware of the Coated Aorta in Fluorodeoxyglucose Positron Emission Tomography-Computed Tomography: A Specific Clue to the Diagnosis of Erdheim-Chester Disease in a Case of Brain and Orbital Lesions with Unknown Primary.

Erdheim-Chester disease (ECD) is a systemic histiocytosis that can involve several organs, with severity ranging from occult to life-threatening. The disease was first described by William Chester in 1930 after working with the Austrian pathologist Jakob Erdheim. Even today, a correct diagnosis of ECD often takes years, given the rarity and variable manifestations of ECD. We present a case of a 63-year-old female presenting with multiple brain lesions, sent for fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography to find primary, and it showed hypermetabolic right occipital brain lesion, right orbital lesion, and soft tissue around the arch of the aorta (coated aorta), and final histopathology of the brain lesion confirmed histiocytosis ECD.