Clinical Images: Erdheim‐Chester disease presenting with palpitations and spondylopathy

The patient, a 43-year-old woman, presented to our hospital with palpations and osteosclerotic spinal lesions disclosed by routine radiological examination. Her physical examination and laboratory results were unremarkable. 18Fluorine-fluorodeoxyglucose-positron emission tomography/computed tomography (18F-PET-CT) showed hypermetabolic activity on vertebrae, sternum, pelvis, scapula, humerus, and femurs and revealed mild pericardial effusion (A). The diagnosis remained ambiguous, after bone marrow smear and two consecutive bone biopsies. Preclinical POEMS syndrome was suspected owing to the osteosclerotic lesions and pericardial effusion. Therefore, the patient was followed. Six months later, her palpitations exacerbated as massive pericardial effusion developed. Cardiac computed tomography after pericardiocentesis revealed a mass invading the right atrium (B). Pathological studies after an open surgery revealed the deposition of “foamy” histocytes surrounded by inflammatory cells (C). Immunohistochemistry was positive for CD163 and CD68 and negative for Langerin and CD1a; the BRAFV600E mutation was detected by molecular testing. Bone scintigraphy showed radioactive concentration of bilateral distal femurs (D), which is omitted by the non–whole-body 18F-PET-CT. Restudy of the original images showed increased glucose metabolism on the right atrium (A). The diagnosis of Erdheim-Chester disease (ECD) was established, and the patient was introduced to a trial of BRAFV600E inhibitor. ECD is a rare and heterogenous non-Langerhans histiocytosis whose diagnosis remains challenging. Bilateral osteosclerosis of the metadiaphysis of the lower-extremity bones is the hallmark of ECD,1 and atypical skeletal involvement, such as the spine, pelvis, ribs, clavicles, and sternum, is common among patients.2 It is crucial to recognize these bone lesions to unmask the underlying cause. We share the lesson learned from a case of misdiagnosis to emphasize head-to-toe workups in this multisystem disorder and call for the awareness of ECD among clinicians, radiologists, and pathologists. Disclosure form Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.