A case of transient abnormal myelopoiesis with trisomy 21, tetrasomy 21, and trisomy 19

Transient abnormal myelopoiesis (TAM) is a transient abnormal leukemoid reaction that occurs in approximately 5-10% of Down syndrome cases. TAM is typically self-limiting, however, it can be life-threatening because of severe pulmonary or hepatic complications. Approximately 20% of these patients develop acute megakaryoblastic leukemia after remission by the age of 4 years. Here, we report a case of TAM with trisomy 21, tetrasomy 21, and trisomy 19. The patient was a 1-day-old male neonate with nuchal translucency measured by fetal ultrasonography at 16 weeks of gestation. He was suspected to have Down syndrome due to his characteristic facial appearance at birth. G-band staining of the peripheral blood when TAM was diagnosed showed trisomy 21, tetrasomy 21, and trisomy 19. The blasts disappeared from the peripheral blood at 4 months of age. G-band staining of the peripheral blood at the time of blast disappearance demonstrated that tetrasomy 21 and trisomy 19 had resolved. It was inferred from the course of the disease that the cells with tetrasomy 21 and trisomy 19 might be blast cells of TAM.