Patient was wrongly diagnosed and repeatedly treated for immune thrombocytopenia for 50 years

We report on a patient with inherited macrothrombocytopenia, MYH9 related disease (MYH9-RD). The patient was wrongly diagnosed and repeatedly treated for immune thrombocytopenia (ITP) for nearly 50 years. Cases of misdiagnosed MYH9-RD and other hereditary thrombocytopenias have been described previously. Typical clinical features such as renal failure and/or progressive loss of hearing should give grounds to suspect hereditary thrombocytopenia. Initial laboratory diagnosis can start with a simple blood smear followed by immunohistochemistry and genotyping. Therapy with thrombopoietin receptor agonists may be beneficial in selected cases of MYH9-RD. ITP treatments including splenectomy are not indicated and may cause harm.