[A case of Erdheim-Chester disease with recurrent relapses requiring differentiation from infectious diseases].

We report a case of Erdheim-Chester disease (ECD) presenting with recurrent mass lesions that posed significant diagnostic challenges. The patient, a 66-year-old man, had multiple recurrent intracranial lesions with contrast enhancement and edema. Given his history of international travel and partial responsiveness to antibiotics, imported infectious diseases were initially suspected. However, infectious etiology was ruled out based on histopathological examination, leading to a diagnosis of ECD. This case was atypical for ECD due to the imaging findings and recurrent nature of the lesions. When granulomatous lesions with histiocytic infiltration are non-infectious, histiocytic disorders should be considered, and immunohistochemical staining is recommended.