BACKGROUND: Acquired hemophilia A (AH) is a rare hemorrhagic diathesis, characterized by the presence of autoantibodies directed against the pro-coagulant activity of factor VIII. It is associated with rheumatoid arthritis (RA) in 4% to 8% of cases and its prognosis remains severe.

CASE REPORT: A 66-year-old patient has been followed up for 20 years for deforming and severe RA, which was in low-disease activity. However, the patient presented a polyarticular flare involving the metacarpophalangeal and the proximal interphalangeal joints, the left elbow, and the right knee, which was warm and swollen. Articular puncture of this knee yielded a hematic fluid that did not coagulate. Its cytological analysis showed significant presence of red blood cells, which were also abundantly present in the other cell lines. Activated partial thromboplastin time was lengthened and not corrected by the addition of control plasma. Prothrombin time (Quick’s test), fibrinogen level, and vitamin K-dependent factors were without abnormalities. In contrast, factor VIII was collapsed at 7% and the anti-factor VIII antibody was positive. The diagnosis of AH with anti-factor VIII inhibitor was thus retained. With regard to RA, the Disease Activity Score was 6.32 and exhibited a very active RA. Rituximab with methotrexate was begun and the evolution was favorable. After 6 months, the reappearance of the anti-factor VIII inhibitor was found, thus justifying a second cycle of rituximab.

CONCLUSIONS: AH is not exceptional in RA. Rituximab remains a relevant alternative for managing simultaneous AH with inhibitor and RA.

Keywords: Arthritis, Rheumatoid, Biological Therapy, Hemophilia A