Affected children are young (peak age ~ 5 yrs) and previously healthy, and they typically present with the sudden onset of petechiae or purpura a few days or weeks after an infectious illness.
Boys and girls are equally affected.
In more than 70% of children, the illness resolves within six months, irrespective of whether they receive therapy.By contrast, ITP in adults is generally chronic.
The bone marrow in patients with ITP contains normal or increased numbers of megakaryocytes.
The diagnosis of ITP remains one of exclusion.
Secondary forms of the disease occur in association with SLE, the antiphospholipid syndrome, immunodeficiency states (IgA deficiency and common variable hypogammaglobulinemia), Lymphoproliferative disorders (CLL, Large granular lymphocytic leukemia, and lymphoma), infection with HIV and hepatitis c virus, and therapy with drugs such as heparin and quinidine.
The guidelines of the American Society of Hematology state that a bone marrow examination is not required in adults younger than 60 yrs of age if the presentation is typical but is appropriate.
Marrow examination is necessary in the presence of atypical features (e.g., those with additional cytopenias, protracted fever, bone or joint pain, unexplained macrocytosis ), or in patients who do not have a brisk or robust response to therapy.