Idiopathic retroperitoneal fibrosis in a patient suspected of impending rupture of the abdominal aortic aneurysm.

Retroperitoneal fibrosis (RPF) is a relatively rare disease which shows a periaortic mass in the retroperitoneal area and predisposes to an obstructive uropathy. We report a case of idiopathic RPF occurring in a patient who was suspected of impending rupture of abdominal aortic aneurysm. A 60-year-old male, with a 2-week history of abdominal pain, was transferred for evaluation of the periaortic mass. Computed tomographic (CT) scan revealed radiological findings such as leakage of contrast media from the aortic lumen and expansion of the periaortic mass. The patient underwent laparotomy, which revealed retroperitoneal fibrotic plaques in the absence of aortic aneurysm. The pathological findings of the biopsy specimen were consistent with idiopathic RPF. The patient received ureteral stent placement and was treated with steroid therapy. When a similar case is encountered, our recommendations are as follows: (i) Both CT scan and magnetic resonance (MR) imaging should be performed to determine whether the retroperitoneal mass is due to idiopathic or secondary RPF. If idiopathic RPF is suspected, the patient should receive primary steroid therapy. (ii) Retroperitoneal periaortic mass indicates a need for the assessment of obstructive uropathy. Early placement of the ureteral stent is necessary for urinary decompression and preservation of the renal function in patients with obstructive uropathy.