Congenital amegakaryocytic thrombocytopenia: the diagnostic importance of combining pathology with molecular genetics.

Congenital Amegakaryocytic Thrombocytopenia (CAMT) is a rare bone marrow failure syndrome that presents with isolated thrombocytopenia within the first year of life. Classic diagnostic bone marrow findings reveal absent or significantly decreased megakaryocytes with otherwise normal marrow cellularity. We present a newborn with thrombocytopenia whose initial bone marrow aspirate showed an appropriate number of megakaryocytes. CAMT was subsequently diagnosed after molecular testing demonstrated a mutation in the thrombopoietin receptor. The presence of a normal number of megakaryocytes on an initial bone marrow aspirate should not exclude CAMT from the differential diagnosis of thrombocytopenia within the first year of life.