Idiopathic thrombocytopenic purpura (ITP): an analysis of 1,122 cases. "Allergic" versus "autoimmune" forms.

Clinical findings, course, complications, outcome, response to treatment and possible pathogenetic mechanisms were evaluated in 1,122 cases of idiopathic (immunological) thrombocytopenic purpura seen over a period of 30 years. Evaluation of clinical and laboratory findings suggests that there are at least two types of idiopathic thrombocytopenic purpura. One, "allergic," is acute in onset, often related to exposure to viral or bacterial infections, is associated with more severe bleeding manifestations in the early stages, is in most cases self-limited, and responds favorably to corticosteroids in the event of very severe bleeding. Antiplatelet factors disappear upon achieving a clinical and hematological remission. The other, "autoimmune," has slow onset of symptoms, chronic course, may respond to corticosteroids and/or immunosuppressive drugs and more often to splenectomy, and is refractory to all therapy in a significant number of cases. Antiplatelet factors remain present even after clinical remission. Both forms are relatively benign processes. However, autoimmune (chronic) cases may show serious hemorrhagic complications and evolve into other autoimmune syndromes and malignant processes.