Idiopathic thrombocytopenic purpura in a boy with ataxia telangiectasia on immunoglobulin replacement therapy.

Ataxia telangiectasia (AT) is an inherited cerebellar degeneration syndrome often associated with immune deficiency, notably, lymphopenia, hypogammaglobulinemia, and cellular immune dysfunction. Although autoimmunity is a common feature of many congenital and acquired immune deficiencies, it has not generally been thought to be associated with AT. We report a 7-year-old boy with AT who developed acute idiopathic thrombocytopenic purpura while on subcutaneous immunoglobulin replacement therapy for hypogammaglobulinemia. He responded promptly to high-dose intravenous immunoglobulin. This case reinforces the notion that one must be observant for autoimmune hematologic conditions in any child with qualitative or quantitative deficiencies in cellular immunity.