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A he term "idiopathic thrombocytopenic purpura(ITP)" has traditionally been used to define an acquired hemorrhagic state due to a marked reduction in the circulating platelet count, in the presence of a normal bone marrow and the absence of an associated systemic disorder. In adults, the immune etiology of the disease has been clearly demonstrated. An autoantibody is produced which binds to platelets, resulting in their removal in the spleen, liver and other sites by cells of the mononuclear (MNP) system.1"3 Because of the autoimmune nature of the disease, it has been suggested that it should be called autoimmune thrombocytopenic purpura (ATP).4 In children, the clinical course of the disease differs from that in adults by its shortness of duration and relatively rapid spontaneous remission and recovery.
HISTORICAL ASPECTS
In 1739, Werlhof identified a distinct disease entity characterized by large purpuric areas. He named it morbus maculosis hemorrhagicus. This entity was further described by Willan in 1808,5 who distinguished ITP purpura - naming it "purpura hemorrhagica" - from other conditions, including "purpura urticans" and Schonlein -Henoch, or anaphylactoid, purpura. The first actual platelet count documenting thrombocytopenia in ITP was performed by Hayden in 1890.
The idea that the spleen plays an important role in the pathogenesis of ITP was considered as early as the days of Hippocrates; but it was only in 1916 that Kasnelson from Prague performed the first splenectomy in a woman with ITP, with total success. The existence of a humoral factor in ITP, and a relatively secondary role of the spleen, was established by Harrington et al.6 He transfused ten normal persons (including himself) with blood from patients with ITP and demonstrated that eight of the recipients promptly developed thrombocytopenia, and some of them purpura as well. The immunologie basis of ITP has been well established only since 1966.
CLASSIFICATION
The most objective system for classifying ITP is to divide it into acute, chronic and recurrent types on the basis of duration.
In acute ITP, the thrombocytopenia is followed by attaining of a permanently normal platelet count within six months of diagnosis; there are no subsequent relapses. This type occurs primarily in children7"9 and represents more than 80 percent of childhood cases of ITP.
In recurrent ITP, the patient has repeated episodes...