ABSTRACT: Retroperitoneal fibrosis (RPF) is an uncommon collagen vascular disease with a male predominance. Back pain with no specific radiation pattern is common, and bilateral obstructive uropathy, potentially reversible, is frequently associated with RPF. We report a case of RPF and review its diagnosis and management.
LOW BACK PAIN is a prevalent problem in the population and can account for up to 15% of all new outpatient visits.  Low back pain is usually a benign condition related to posture or physical strain and generally spontaneously resolves or is easily treated with analgesics, with or without physiotherapy. Therefore, low back pain is often not regarded as a symptom of serious disease. We recently encountered a case of RPF in a 55-year-old man after he had had 6 weeks of low back pain. Clearly, the symptoms of progressive low back pain, increasing malaise, easy fatigability, nausea, vomiting, and reduction in urinary output prompted his coming to our emergency department. Computed tomography (CT) or magnetic resonance imaging (MRI) evidence of periaortic soft tissue mass in this clinical setting, in conjunction with an elevated erythrocyte sedimentation rate (ESR) are consistent with the diagnosis of RPF.  However, tissue biopsy and histologic confirmation remain the mainstay of diagnosis. Corticosteroids or other immunosuppressive agents in combination with prompt surgical treatment can lead to remarkable renal salvage and reduction in morbidity.
A 55-year-old white man came to our emergency department after 6 weeks of low back pain. He did not think it was anything more than a sprain and took occasional acetaminophen or ibuprofen tablets for temporary pain relief. In the week before admission, he had constitutional symptoms of malaise and vague fevers with anorexia, nausea, and vomiting, and, lately, oliguria. He denied any joint symptoms, rash, or respiratory symptoms. There was a remote history of recurrent gout and the administration of allopurinol for several years. Allopurinol had been discontinued nearly 10 years previously. Hypertension had been controlled with lisinopril, 20 mg daily. He had no history of drug allergies, previous malignancy, abdominal surgical procedures, connective tissue disease, migraine, or intake of any other vascular medications. The patient denied any history of radiation or other unusual chemical exposure.
Physical examination was unremarkable except for limited bilateral basal rales, which improved on coughing, and a mildly swollen scrotum. There was no abdominal distension, and no masses were palpable. No rash was evident, and the musculoskeletal system was intact.
Admission laboratory values were white blood cell count 8.2 x [10.sup.9]/L, hematocrit 37.1%, platelet count 565,000/[mm.sup.5], potassium 5.6 mEq/L, [CO.sub.2] 21 mEq/L, albumin 4.6 g/dL, globulin 4.5 g/L, magnesium 3.7 mg/dL, total calcium 8.8 mg/dL with ionized fraction of 4.04 mg/dL, phosphorus 7.2 mg/dL, serum urea nitrogen (SUN) 56 mg/dL, serum creatinine...