Transient Abnormal Myelopoiesis in a Down Syndrome Baby: A Case Report

Abstract

Transient Abnormal Myelopoiesis (TAM) is a transient haematological condition observed in children with Down syndrome during their neonatal period. Spontaneous resolution without any specific treatment is the rule, and the condition is known to occur exclusively in association with trisomy 21. Around 10% of Down syndrome babies are known to be affected by TAM, and 20-30% of these babies are known to develop acute myeloid leukaemia, of the megakaryoblastic type, in their later lives. Multisystem involvement is known in this condition. The present case of TAM is a two-day-old newborn female baby, born out of full-term gestation, presented with respiratory distress along with congenital pneumonia, hepatosplenomegaly, and mild ascites. The baby also had significant pulmonary hypertension, an Atrial Septal Defect (ASD), and non restrictive Patent Ductus Arteriosus (PDA). A significant increase in the total leukocyte count was seen, accompanied by thrombocytosis and 72% blastoid cells. Then, using karyotyping, Trisomy 21 was verified. 35% of the blasts had megakaryoblastic differentiation, according to flow cytometry. Hence, before diagnosing congenital leukaemia based on finding excess blasts in the peripheral smear of a newborn, karyotyping has to be done to look for possible trisomy 21. It can be an incidental finding, as in the present case, without prior clinical suspicion of Down syndrome.

Keywords

• acute megakaryoblastic leukaemia
• congenital leukaemia
• flow cytomery
• karyotyping
• trisomy 21