Haema 2010; 1(2): 204-214
by Katerina Megalakaki
Department of Haematology, Metaxa Cancer Hospital, Piraeus, Greece
Abstract
Immune thrombocytopenia (ITP) is an aquired autoimmune disorder characterized by accelerated destruction of antibody-coated platelets in the macrophage system situated mainly in the spleen. It is now recognized that a small proportion of patients have to be treated, i.e. those with platelets <30×109/L and/or significant bleeding manifestations. New insight in the pathophysiology has revealed that apart from the development of autoantibodies against platelet glycoproteins, insufficient platelet production and abnormalities of cellular mechanisms of immune modulation are responsible for the emergence of the disease and probably the failure of immunomodulation-oriented treatment. Patients with severe primary ITP not responding to the first-line treatment with courses of corticosteroids, or demanding continuous treatment with unacceptable high doses for more than 6 months are candidates for second-line treatment, either medical or splenectomy. The decision must be individualized, based on age, status performance and the patient’s willing among others. Up to now splenectomy is the only treatment with very good long-term results in primary ITP. It is performed after 6-12 months of medical treatment because many patients are late responders. Laparoscopic splenectomy is a safe procedure with low mortality and acceptable peri-operational morbidity. About two third of patients achieve complete or partial remission, while one third relapse, most of them within two years after the splenectomy and several patients many years later. 14% are non-responders. There is no prognostic association between the response to splenectomy and several parameters, i,e. age, response to corticosteroids, IVIG or the site of platelets destruction. Impaired megakaryopoiesis, the presence of additional immune disorders and the presence of accessory spleen are responsible for failure or relapse after splenectomy. Splenectomised patients are at high risk of post-splenectomy overwhelming infection, which is rare but may be fatal. Patients should be immunized at least 15-20 days before splenectomy. Also, they should be educated to seek medical advice in febrile illness no matter how trivial it may be as soon as possible. Asplenic patients are also in long-term risk of thromboembolic disease. Children are seldom treated with splenectomy since they often present spontaneous remissions or late responses. Also they are in increased risk of fatal post-splenectomy infections. Splenectomy results are comparable with adult patients. Nowadays less splenectomies are performed, partly because fewer patients are treated, partly because older or less fit patients are given the option of medical treatment with new immunomodulating agents such as the monoclonal anti-CD20 antibody and the new thrombopoietic agents. This kind of treatment offers long enough remissions to postpone and/or eventually cancel elective splenectomy for certain patients with ITP. Although the combination of these drugs looks promising as they are tolerable, effective and safe, their side effects after long term administration are not known. Αlso the new drugs are costly and consequently inappropriate for long-term treatment. However they have made a breakthrough in the treatment of adult patients with ITP, pushing splenectomy aside which is practically reserved for selected individuals.