Case Report: Acquired hemophilia A presenting with recurrent arthritis-like joint swelling and musculoskeletal hematomas-a focused literature review.

Background: Acquired hemophilia A (AHA) usually causes cutaneous, soft-tissue, or muscle bleeding; joint-dominant presentations are uncommon and may be mistaken for septic or inflammatory arthritis. Case presentation: A man in his late 60s with no personal or family bleeding history developed recurrent arthritis-like joint swelling, extensive bruising, and suspected iliopsoas, upper-arm, and thigh hematomas after an elective operation. For approximately 4 months, fever, raised inflammatory markers, and periarticular imaging abnormalities led to repeated infection-directed treatment. At specialist assessment, the activated partial thromboplastin time was 77.6 s. A mixing study showed greater prolongation after incubation, factor VIII activity was below 0.8%, and the factor VIII inhibitor titer exceeded 120 Bethesda units, establishing AHA. Intravenous methylprednisolone followed by a prednisone taper and two rituximab infusions was followed by cessation of new bleeding and improvement in joint symptoms. At approximately 5 months after starting immunosuppression, the inhibitor was undetectable, factor VIII activity had recovered to 27%, and the activated partial thromboplastin time was within the reporting laboratory's reference range. At telephone follow-up approximately 13 months after treatment began, he reported clinical stability for about 6 months after stopping all medications, apart from occasional brief right-knee pain; contemporaneous coagulation results were unavailable. Repeated ceftriaxone exposure was considered a possible associated factor, but causality was not established because an activated partial thromboplastin time of 40 s was documented before the first recorded postoperative exposure and later antibiotic exposures were incompletely documented. Conclusion: In an older adult, recurrent hot or swollen joints accompanied by deep-muscle bleeding and an unexplained prolonged activated partial thromboplastin time should prompt immediate factor VIII activity and inhibitor testing. This case documents inhibitor clearance with partial factor VIII recovery and subsequent patient-reported stability off treatment; it does not prove drug causality or the comparative efficacy of rituximab.