Macrophage activation syndrome (MAS) is a severe complication of chronic rheumatic diseases, particularly juvenile rheumatoid arthritis. However, MAS is rarely described in adult rheumatoid polyarthritis.
We report a case of MAS complicating a seropositive rheumatoid polyarthritis after 20 years of evolution. Pancytopenia with fever, renal failure and hepatic dysfunction revealed the disease that was confirmed by multiple macrophages and monocytes invading the bone marrow specimen.
Outcome has been spectacular under corticosteroids.