[The 487th case: prominent eyes, headache, blurred vision]

One 51 years old man was admitted to the rheumatology department with a history of prominent eyes, headache and blurred vision for half year. The main manifestations included retrobulbar inflammatory pseudotumor and retroperitoneal fibrosis. He was initially diagnosed as granulomatosis with polyangiitis. Prednisone and cyclophosphamide were administrated and effective. New mass of dura mater and osteosclerosis presented during follow up. Finally Erdheim Chester disease(ECD) was diagnosed by biopsy and pathological examination. Vemurafenib, a v-raf murine sarcoma viral oncogenes homolog B1 (BRAF) inhibitor, 480 mg was given twice a day. The patient's condition is stable and still in follow-up. Although ECD is a rare histiocytosis, clinicians should pay attention to its manifestations and differential diagnoses.