AP-VAS 2012 case report: two patients with rheumatoid arthritis suspected of relapsed microscopic polyangiitis after initiation of dialysis.

We report two patients with rheumatoid arthritis (RA) who were suspected of microscopic polyangiitis during maintenance dialysis. Case 1 was a 52-year-old woman with RA diagnosed at the age of 38 years and treated successfully with gold compounds. At the age of 43 years, she presented with progressive renal dysfunction and abnormal urine sediments, and a renal biopsy revealed crescentic nephritis with advanced glomerular sclerosis. Myeloperoxidase antineutrophil cytoplasmic antibody (MPO-ANCA) was not measured on that occasion. She reached end-stage renal failure within 4 months and started peritoneal dialysis. Eight years later, soon after she was switched to hemodialysis, she developed fever of unknown origin. MPO-ANCA was elevated to 37 EU, although there were no other signs or symptoms suggestive of vasculitis. After taking prednisolone orally (10 mg/day), her fever withdrew, and MPO-ANCA became undetectable. Case 2 was a 71-year-old woman with RA diagnosed at the age of 60 years and treated with gold compounds. She developed renal failure of unknown cause (no biopsy was performed), and started hemodialysis at the age of 69 years. One year later, she presented with fever and subsequently developed cough with hemoptysis. MPO-ANCA was elevated to 62 EU. Treatment with azathioprine 50 mg and prednisolone 35 mg daily brought remarkable clinical improvement, and MPO-ANCA became undetectable. These cases highlight the importance of measuring ANCA even in RA patients on dialysis who present with fever of unknown origin or with underlying kidney disease of uncertain etiology.