Adolescent IgG4-related retroperitoneal fibrosis with left lower extremity edema as the first symptom: A case report.

IgG4-related retroperitoneal fibrosis is a type of IgG4-related diseases. The etiology is still unclear. It is often classified as idiopathic retroperitoneal fibrosis, but the pathological process and clinical results between them are different. Therefore, the differential diagnosis of them is very important. An 18-year-old patient was admitted to the Second Xiangya Hospital of Central South University due to "left lower extremity edema for 1 and a half month" on December 19, 2019. In examination of PET/CT, the starting point of the left aorta-intra-thoracic artery showed a soft tissue density lump with increased sugar metabolism, which indicated a suspected malignant tumor, and dilatation of the left renal pelvis and ureter. On January 8, 2020, the patient was performed pelvic edema excision, ureterectomy and anastomosis. The postoperative examination results were considered as IgG4-related disease. As a rare systemic disease, early correct diagnosis and precise and individualized treatment can alleviate the suffering of patients and ensure that patients are minimally traumatized.