Whole body positron emission tomography-MRI of Erdheim-Chester disease: a case report

Erdheim-Chester disease (ECD) is a rare non-Langerhans cells systemic histiocytosis characterized by multiple lesions that can involve several organs and systems [including central nervous system (CNS), bones, skin, heart and vessels] and produce a highly heterogeneous clinical picture (1). Therefore, a correct patient diagnostic work-flow has to be based on a multidisciplinary approach, including the clinical examination, histopathology and integrated imaging (2). Indeed, imaging plays a key role in the diagnosis of ECD, often requiring the combination of bone scintigraphy for skeletal assessment (1), radiography (RX), computed tomography (CT), and magnetic resonance imaging (MRI) for characterization of specific organ involvement (3), and F-fluorodeoxyglucose (F-FDG) positron emission tomography (PET)-CT for systemic evaluation and treatment assessment (4). To date, combined PET-MRI is the most complex and sophisticated hybrid imaging platform available wholebody imaging assessment. PET-MRI combines molecular information of PET with excellent anatomic details of MRI systems and overcoming limitations of each modality alone (5). We here describe for the first-time simultaneous PETMRI findings in a patient affected by ECD, showing multisystemic involvement in a single shot imaging session.