Changing Spectrum of Chronic Immune Thrombocytopenic Purpura: New Face for an Old Disease

Characterized by low platelet counts, immune thrombocytopenic purpura (ITP) has been discovered to be an acquired autoimmune disorder since the mid-1900s (Evans et al., 1951). In the 21st century, the modern generation would shudder at Harrington and Hollingsworth’s experiment they performed to search for the pathogenesis of ITP. By injecting themselves with 500 ml of blood from a patient from low platelet counts, they developed the same bleeding disorder and were able to reproduce the disease in themselves (Harrington et al., 1951). Since that experiment, the pathogenesis and the therapeutic options of ITP have evolved by leaps and bounds. The traditional model of ITP is that of pathologic destruction of platelets by antiplatelet antibody. For many decades, this model of autoimmune thrombocytopenic purpura has shaped our understanding of the disorder and our therapeutic management of ITP (Buchanan et al, 1977, Hou et al. 1995, Fujisawa K et al. 1992). Recent studies have broadened our perspective beyond humoral dysregulation to include the cellular immune system and abnormalities of megakaryocytes as well (Olsson, et al., 2003, Ballem et al., 1987, McMillan et al., 2004). These recent findings have opened the door for new treatment possibilities for ITP. In contrast to a more predictable clinical course of acute ITP, the pathogenesis, natural history and management of chronic ITP are significantly more diverse and rapidly evolving. The established treatment practices for chronic ITP have also undergone a major change. After a long period of standard treatment approach using steroids, splenectomy, and immunosuppressive therapy, a breakthrough came with the use of B-cell depletion therapy (Cines and McMillan, 2005). The availability of monoclonal antibody, rituximab, has led hematologists to reconsider the role of splenectomy in the frontline management of chronic ITP (Arnold et al., 2007). A new era has begun with the development of thrombopoietinmimetic agents that stimulate megakaryocytes to grow and produce platelets (Nurden et al., 2009). Since chronic ITP remains a heterogeneous disorder; there is no consensus on the definite diagnostic criteria and management. In 1996, the American Society of Hematology published a landmark paper recommending guidelines to assist clinicians in the management of ITP (George et al., 1996). Since then, there have been tremendous advances in the management of both adult and pediatric ITP. These guidelines were updated by the