An Asian male in his 60s presented for a nephrology consultation. Five years ago he sought medical care with complaints of indolent fatigue, nausea, and vague abdominal pain.
Labs done at the time revealed a creatinine elevated to 3.5mg/dL with no prior known renal disease. Imaging revealed bilateral hydronephrosis secondary to a mass. Tissue biopsy of the mass reportedly demonstrated significant mononuclear cell infiltrates in retroperitoneal, peri-vascular regions.
He was eventually started on prednisone. He had no other significant medical history except hypertension. Current medications included only low-dose prednisone. He denied smoking, and has no family history of kidney disease.
On exam, he is hypertensive with a blood pressure of 160/80 mm Hg. He had no flank pain on palpation, no leg edema, and no other significant exam findings.
Current diagnostic data included the following: WBC is 5,600, hemoglobin 14 g/dL, platelet count 172,000. Creatinine level was 1.2 mg/dL. Potassium and CO2 were within normal limits. Urine was bland without protein or cells.
Computed tomography of the abdomen and pelvis was performed and representative images are shown.
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Computed tomography findings in this patient demonstrate mesenteric, retroperitoneal, and peri-aortic lymphadenopathy. The images show a circumferential, amorphous mass of soft tissue in the retroperitoneum surrounding the abdominal aorta.
The imaging, combined with the clinical history and biopsy findings, are consistent with retroperitoneal fibrosis, presumptively idiopathic.
Idiopathic retroperitoneal fibrosis (RF) occurs is about 1 in 100,000 individuals. It is found more commonly after the 4th decade of life, with male predominance.
In addition to the drugs listed above, RF has been linked with a variety of substances and conditions. Lymphomas, metastatic solid tumors, tuberculosis, tobacco, asbestos exposure, and radiation therapy have all been linked with RF.
In a subset of affected patients, RF may be a component of IgG4 related disease. In such cases, tissue biopsy immunohistochemistry would show a IgG4 positive plasma cell infiltrate.
Patients with RF may present with flank or back pain, elevated creatinine/acute kidney injury, and/or with radiographic evidence of retroperitoneal, peri-aortic tissue mass with or without adjacent lymphadenopathy.
Computed tomography is the imaging modality most commonly used to make a diagnosis. Hydronephrosis due to ureteral obstruction may also be present. Tissue biopsy of the mass is performed to confirm the diagnosis and to rule out malignancy or atypical infection.
Steroid therapy is usually the primary mode of treatment. IgG4-related RF in particular is usually steroid responsive. A number of case reports and a few prospective studies have examined the effectiveness of other agents.
One recent prospective study of 28 patients with RF investigated the combination of steroids and mycophenolate noting reduction in mass size, and lab markers. Tamoxifen has been used to treat RF.
One recent study noted more frequent disease flares when prednisone was rapidly withdrawn after remission, and the patient switched to tamoxifen. Case reports of success with rituxamab have also been noted.
This case was prepared by Kevin T. Harley, MD, Assistant Clinical Professor of Medicine, Division of Nephrology & Hypertension, at the University of California in Irvine.
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