History: A 63-year-old man developed a Churg-Strauss syndrome with predominantly motor-sensory polyneuropathy. Initial treatment with cyclophosphamide and steroids achieved complete remission. Subsequent relapse with marked retinal vasculitis at first was refractory to the standard treatment. Renewed remission was obtained with additional infliximab, and was maintained with azathioprine for 12 months before the patient again presented with symmetrical polyarthritis.
Investigations: Clinical examination revealed a symmetrical polyarthritis involving the joints of the hand and fingers. The acute-phase parameters were raised, the rheumafactor was highly positive. Radiology showed early erosions in the bones of the hand. There were no indices of renewed activity of the Churg-Strauss syndrome.
Treatment and course: These findings indicated sero-positive rheumatoid arthritis and methotrexate was started, later supplemented with sulfsalazine and hydroxychloroquine because of continuing signs of activity. Infliximab was again given because of further progression, but a severe infusion reaction developed during the second infusion. After changing to etanercept remission of the rheumatoid arthritis was achieved.
Conclusion: The development of rheumatoid arthritis during remission achieved with azathioprine in Churg-Strauss syndrome of four-year duration is very rare. Repeated dosis of infliximab at long intervals greatly increases the risk of an intolerance.