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

Background: 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.

Case report: 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.

Conclusion: It was inferred from the course of the disease that the cells with tetrasomy 21 and trisomy 19 might be blast cells of TAM.