Learning from errors: when a low platelet count in neonate excludes immune thrombocytopenic purpura in mother

This paper reviews the most common causes of thrombocytopenia in the newborn. It mentions few classification schemes that clearly characterize the most common causes, diagnosis and treatment approaches for neonatal thrombocytopenia. Particular attention is paid to inborn macrothrombocytopenia without congenital anomalies. They represent a rare group of diseases, often captured randomly or during routine examinations. An attention is paid on congenital macrothrombocytopenia variants with mutations in the MYH9 gene. If they are not associated with other disorders (deafness, presenile cataracts, nephritis or renal failure), they may be mistakenly diagnosed as the acquired immune thrombocytopenic purpura (ITP). This distinguishing is essential to avoid potentially harmful and unnecessary treatment. The listed case report points to a situation where a detection of the root causes of neonatal thrombocytopenia led to a review of misdiagnosed ITP in the mother. A platelet size evaluation by both an appropriate cell counter and blood film examination is useful for differentiating a heterogeneous group of rare inherited macrothrombocytopenias. A healthy twin supported autosomal dominant inheritance. The results of investigations of twins and mother confirmed the congenital/inherited macrothrombocytopenia from the group of MYH9-related diseases (Tab. 5, Fig. 2, Ref. 21).