A hypereosinophilic syndrome mimicking rheumatoid arthritis

A 58 year old white man presented with an articular syndrome that appeared clinically to be rheumatoid arthritis with nodules. Lack of response to therapy, and laboratory and pathologic data failed to confirm the diagnostic impression. The patient's course over the ensuing seven years was compatible with the hypereosinophilic syndrome. The articular involvement represented soft tissue and synovial fibrinoid degeneration with eosinophilic infiltration. This is the first reported case of articular involvement in the hypereosinophilic syndrome and adds it to the list of processes that can cause hand deformity resembling rheumatoid arthritis.