SummaryAcquired hemophilia is a rare autoimmune disorder characterized by bleeding that occurs in patients with a personal and family history negative for hemorrhages. Autoimmune disorders occur when the body's immune system mistakenly attacks healthy cells or tissue. In acquired hemophilia, the body produces antibodies (known as inhibitors) that attack clotting factors, most often factor VIII. Clotting factors are specialized proteins required for the blood to clot normally. Consequently, affected individuals develop complications associated with abnormal, uncontrolled bleeding into the muscles, skin and soft tissue and during surgery or following trauma. Specific symptoms can include nosebleeds (epistaxis), bruising throughout the body, solid swellings of congealed blood (hematomas), blood in the urine (hematuria) and gastrointestinal or urogenital bleeding. Acquired hemophilia can potentially cause severe, life-threatening bleeding complications in severe cases. In approximately 50% of cases, there is an identifiable underlying clinical condition; in the other 50% no cause is known (idiopathic).
IntroductionAcquired hemophilia is different from congenital hemophilia, a group of rare genetic disorders caused by congenital deficiency of certain clotting factors. The main form of hemophilia is hemophilia A (classic hemophilia), which is an X-linked disorder that fully affects males only. It is caused by deficiency or inactivation of factor VIII, the same clotting factor that is affected in most cases of acquired hemophilia. Although both disorders involve deficiency of the same clotting factor, the bleeding pattern is quite different. The reason the bleeding patterns differ between these disorders is not fully understood.