Objective: To investigate the clinical and imaging characteristics of an inflammatory myeloid neoplasm-- Erdheim-Chester disease (ECD). Methods: The clinical and imaging data from 6 patients with pathology -confirmed ECD visited Ruijin Hospital, Shanghai Jiao Tong University during March 2019 to February 2022 were retrospectively analyzed. Results: The age of 6 ECD patients ranged from 11 to 64 years, of which 4 were young, aged 11 to 33 years. The ratio of male to female was 2∶1. The main symptoms were central diabetes insipidus（2 cases）, ataxia（2 cases）, lower limb pain （3 cases）and periorbital yellow plaques （3）. The skeletal system was involved in 5 of 6 cases. All 6 cases involved extra-skeletal systems, including skin and subcutaneous soft tissue (n=5), central nervous system (n=2), cardiovascular system (n=2), chest (n=2, including 1 with lung adenocarcinoma), retroperitoneal mass (n=1) and renal fibrosis (n=1).Among 6 cases of ECD, 2 cases were diagnosed as ECD on the imaging, and 1 case as xanthogranuloma in the eye, and 3 other cases that could not tell on the imaging. For clinical diagnosis,2 patients were clinically misdiagnosed as having malignant tumors, but the disease type was not clearly identified. A case with false negative result in both lower limbs on initial X-ray imaging, and CT examination showed bone sclerosis. In patients with ECD, the characteristic X-ray and CT findings of the skeletal system were symmetric bone sclerosis of the long bones of both upper and lower limbs, while non-characteristic X-ray and CT findings were osteolytic bone destruction. Multiple extra-skeletal lesions showed abnormalities in density, signal and radioactivity concentration. Conclusions: Erdheim-Chester disease usually presents with central diabetes insipidus and ataxia, accompanied by cutaneous xanthogranuloma and other skin lesions. The main imaging manifestation of ECD is osteosclerosis of both lower extremities, with multiple system involvement.