Computed tomography (CT) showed bilateral ureteral obstruction in the mid-ureter with thickening of tissue around the great vessels.
A 61-year-old man with no significant past medical history presented to the hospital with bilateral flank pain and 20 lbs weight loss in the previous few months. Computed tomography (CT) showed bilateral ureteral obstruction in the mid-ureter with thickening of tissue around the great vessels. There were no stones. These findings are consistent with retroperitoneal fibrosis. Retrograde ureterogram showed 4 cm ureteral strictures bilaterally with medial deviation. Bilateral stents were placed. Serum creatinine improved from 1.37 to 1.27 after stent placement. However, in the subsequent month, the patient continued to have flank pain. Repeat CT scan showed bilateral hydronephrosis in the presence of ureteral stents (Figure 1). There was ill-defined soft tissue mass-like thickening, consistent with known diagnosis of retroperitoneal fibrosis.
Labs showed BUN 85, serum creatinine 12 mg/dL and potassium 5.8 mEq/L. Bilateral nephrostomy tubes were placed. There was robust urine output via bilateral nephrostomy tubes. His creatinine decreased to 2.6 mg/dL 3 days later and continued to decline to 1.53 mg/dL 1 month later. He underwent CT-guided fine needle aspiration of retroperitoneal soft tissue. There were a few fibrous cells present that stained positive for beta catenin. No malignant cells were found. The pathology is essentially consistent with chronic inflammation and fibrosis. Patient was started on prednisone and mycophenolate mofetil for treatment of idiopathic retroperitoneal fibrosis.
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This case was prepared by Yongen Chang, MD, PhD, Assistant Clinical Professor, Division of Nephrology and Hypertension, University of California-Irvine.
2 Zen Y, Sawazaki A, Miyayama S, et al. A case of retroperitoneal and mediastinal fibrosis exhibiting elevated levels of IgG4 in the absence of sclerosing pancreatitis (autoimmune pancreatitis). Human Pathol. 2006;37:239-243. doi:10.1016/j.humpath.2005.11.001.
Retroperitoneal fibrosis is a rare disease often leading to obstructive uropathy and renal failure. It is most often idiopathic but can be associated with 1) malignancy such as Hodgkin’s and Non-Hodgkin’s lymphoma; 2) drugs including hydralazine, ergot-derivatives, methysergide, bromocriptine, beta blockers, methyldopa, hydralazine, analgesics, and biologic agents such as TNFα blockers; 3) infections such as tuberculosis; 4) prior abdominal surgery or trauma; 5) radiation therapy directed to the abdomen; 6) smoking and asbestos exposure; 7) Erdheim-Chester disease (also called polyostotic sclerosing histiocytosis) characterized by histiocyte proliferation of the bone marrow causing long bone sclerosis. The key to evaluating retroperitoneal fibrosis is to exclude secondary causes as listed above. Imaging and/or biopsy are often required to confirm the diagnosis and to look for potential malignancy or infection.
The pathogenesis of idiopathic retroperitoneal fibrosis is unclear but is thought to be a manifestation of a systemic autoimmune disease such as immunoglobulin G4-related disease (IgG4-RD). IgG4-RD is a multisystem disease that leads to inflammation, swelling, and fibrosis of the involved organs, including the pancreas, salivary glands, lymph nodes, pituitary gland, and the mediastinum.1 In patients with IgG4-RD, biopsy samples of retroperitoneal tissue or other involved organs demonstrate infiltration of immunoglobulin G4 (IgG4)-producing plasma cells.2,3 Glucocorticoid is the initial therapy for idiopathic retroperitoneal fibrosis. For those who do not respond to glucocorticoids, additional immunosuppressants have been used with some success in case reports. These include azathioprine, methotrexate, mycophenolate mofetil, cyclphosphomide and cyclosporine. However, there have been no clinical trials directly comparing these agents (in combination with glucocorticoids) to glucocorticoids alone.