A Case of Idiopathic Retroperitoneal Fibrosis Associated With Sjögren's Syndrome.

After presenting with nonspecific symptoms, a 52-year-old female was found to have a 3.4 × 2.6 cm retroperitoneal mass resulting in hydronephrosis on abdominal computed tomography scan. After extensive workup including surgical debulking, excisional biopsy, and autoimmune panel, she was found to have idiopathic retroperitoneal fibrosis (IRF) with negative staining for immunoglogulin G4 (IgG4). Two years after presentation, the patient developed dyspnea, cough, and xerostomia. Repeat anti-Sjögren Syndrome A and anti-Sjögren Syndrome B titers and labial gland biopsy confirmed the diagnosis of concomitant Sjögren's syndrome (SS). The patient was treated with mycophenolate mofetil with improvement in her symptoms. Most cases of retroperitoneal fibrosis are associated with IgG4-related disease or other autoimmune disease. To our knowledge, this is only the second reported case of SS associated with IRF. Because symptoms of IRF are nonspecific, there is often a delay in diagnosis resulting in end-organ disease such as ureteral obstruction or hydronephrosis. Although IRF is uncommon, it should be considered in patients presenting with abdominal or flank pain, especially in patients with concomitant autoimmune disorders. Early recognition of disease can prevent end-organ damage and, as more cases are diagnosed, its relationship to SS may be elucidated leading to further advances in treatment and surveillance.