RESUMEN
BACKGROUND Acquired hemophilia is a rare but potentially dangerous bleeding disorder caused by autoantibodies against coagulation factors. It affects 1 to 1.5 per 1 million people each year. While 50% of cases could be idiopathic, other causes include malignancies, diabetes, pregnancy, infection, and autoimmune disorders. CASE REPORT We report a case of a 90-year-old male who developed a spontaneous hematoma on the dorsum of his right hand, with no prior history of trauma or any other mucosal bleeding. His activated partial thromboplastin time (aPTT) was found to be prolonged (>180 seconds) with a very low level of factor VIII (0.1%). CONCLUSIONS As workups did not identify the source, including malignancy and autoimmune diseases, of his acquired hemophilia, it is believed to be idiopathic. He was started on intravenous recombinant factor VIIa (NovoSeven) to control the bleeding in combination with an immunosuppressive therapy of cyclophosphamide and prednisolone. In approximately 10% of patients with acquired hemophilia, underlying malignancy, such as squamous cell cancer, chronic lymphocytic leukemia, non-Hodgkin lymphoma, and multiple myeloma can present and commonly develop in elderly patients. Therefore, patients diagnosed with idiopathic acquired hemophilia should be given long-term follow up.