Multimodality imaging of spleen involvement in Erdheim-Chester disease mimicking splenic hemangioma: a unique case report.

Erdheim-Chester disease (ECD) is a rare and clinically heterogeneous non-Langerhans cell histiocytosis, and its diagnosis relies on established clinical, radiologic, histopathological criteria. ECD can be evaluated by whole-body preoperative imaging methods. Although ¹⁸F-FDG PET/CT shows negative findings in some splenic benign or borderline lesions, such as splenic inflammatory myofibroblastic tumors and hemangioendotheliomas, it can provide value in differentiating some malignant diseases, such as hemangiosarcoma and metastases. Here, we report the CT, MRI, and ¹⁸F-FDG PET/CT imaging performance of an ECD patient who presented with only spleen involvement. Even though some clinical and radiological descriptions can be found in the literature, ECD reports with only splenic involvement mimicking splenic hemangioma as the first presentation are rare, to the best of our knowledge. Histopathology and molecular analysis of this case confirmed the diagnosis of ECD. Clinicians should pay attention to the possibility of ECD occurrence in the spleen, while negative findings on ¹⁸F-FDG PET/CT of the spleen indicated a low risk for high-grade malignant splenic tumors and metastases.