埃尔德海姆-切斯特病 (ECD) 是一种罕见的多系统炎症性非朗格汉斯细胞组织细胞肿瘤。丝裂原激活蛋白激酶信号通路（最常见的是 BRAFV600E）中复发性体细胞突变的发现导致 ECD 从炎症性疾病重新分类为肿瘤过程。目前已纳入修订后的 2016 年世界卫生组织造血肿瘤分类以及修订后的组织细胞学会 2016 年组织细胞增多症分类中的 Langerhans 组。当出现症状时，ECD 最常表现为骨痛和疲劳。此外，还经常遇到神经系统表现、中枢性尿崩症、眼球突出和眶周黄斑瘤样病变。病理结果可能因活检部位而异，并可能显示一系列特征。因此，由于不同的临床表现和不同的组织学发现，影像学通常可以显示该疾病的第一个迹象。然而，放射学检查结果需要结合临床和组织学检查结果来解释，以确立 ECD 的诊断。从提供促进诊断的经典发现到帮助放射科医生确定疾病的程度和预测预后，放射学在 ECD 中的作用随着对疾病本身的了解而不断发展。对分子发病机制的深入了解和靶向治疗药物的开发以及维莫非尼和考比替尼的批准使得 ECD 管理指南的修订成为必要。作者使用基于器官系统的方法讨论了 ECD 的各种放射学发现和鉴别诊断，并从放射科医生的角度简要描述了基于 ECD 国际医学研讨会修订后的评估、诊断和治疗共识建议。 ©RSNA，2024 本文提供了补充材料。完整的数字演示可在线获取。

Erdheim-Chester disease (ECD) is a rare, multisystemic, inflammatory, non-Langerhans cell histiocytic neoplasm. The discovery of recurrent and somatic mutations in the mitogen-activated protein kinase signaling pathway, most commonly BRAFV600E, has led to a reclassification of ECD from an inflammatory disorder to a neoplastic process. It is now included in the revised 2016 World Health Organization classification of hematopoietic tumors and in the Langerhans group in the revised 2016 Histiocytosis Classification of the Histiocyte Society. When symptomatic, ECD most commonly manifests with bone pain and fatigue. Also, neurologic manifestations, central diabetes insipidus, exophthalmos, and periorbital xanthelasma-like lesions are frequently encountered. Pathologic findings may vary depending on the site of biopsy and may display a spectrum of features. Thus, due to the diverse clinical presentation and variable histologic findings, imaging can often show the first sign of the disease. Radiologic findings are, however, interpreted in conjunction with clinical and histologic findings to establish the diagnosis of ECD. From providing classic findings that facilitate diagnosis to helping radiologists determine the extent of disease and predicting a prognosis, the role of radiology in ECD has evolved with the understanding of the disease itself. Insights into the molecular pathogenesis and the development of targeted therapeutic agents along with approval of vemurafenib and cobimetinib have necessitated revision of the guidelines for the management of ECD. The authors discuss various radiologic findings of ECD and differential diagnoses by using an organ system-based approach and briefly describe the revised consensus recommendations for evaluation, diagnosis, and treatment based on the International Medical Symposia on ECD from a radiologist's perspective. ©RSNA, 2024 Supplemental material is available for this article. The full digital presentation is available online.