Erdheim-Chester disease (ECD) is a rare, multisystemic, idiopathic disease often associated with BRAF V600E mutation. Its diagnosis is typically delayed and challenging due to its variable manifestations. Although it has an indolent course, advanced stages can manifest fulminant behavior with multiple vital organ involvement. It is a class 2a, non-Langerhans cell histiocytosis with characteristic radiological appearance. Whole body imaging might be helpful, particularly, to assess skeletal lesions. Although widespread disease with typical skeletal involvement on imaging can prompt diagnosis, histopathology with immunohistochemistry is required for confirmation. The disease can also manifest itself with a large variety of central nervous system related or orbital symptoms. Cardiac involvement is quite common. We present an interesting image of a patient with ECD who underwent PET/CT. Informed consent of the subject described in this image is waived by the Institutional Review Board.