Transient myeloproliferative disorder in Down syndrome presenting with ascites: a case report

BACKGROUND: An increased frequency of acute myelogenous leukemia is a well known feature in children with Down syndrome. In addition, transient myeloproliferative disorders (TMD), which may mimic acute leukemia, also occur in neonates with Down syndrome. TMD is recognized shortly after birth or in the neonatal period and is characterized by leukocytosis and thrombocytopenia, which resolve spontaneously in four to six weeks. CASE: A 1.5-month-old, male infant born with Down syndrome and patent ductus arteriosus presented with abdominal distention due to ascites. Cytology of the fluid revealed immature myeloid cells and megakaryocytes. Flow cytometry of the ascitic fluid confirmed the presence of immature myelomonocytic cells. A complete hematologic evaluation along with the clinical findings supported the diagnosis of TMD in Down syndrome. CONCLUSION: TMD is an uncommon syndrome strongly associated with Down syndrome. Since the abnormal laboratory findings are seen primarily in the peripheral blood, it is usually diagnosed by a hematopathologist without much difficulty. Our case demonstrates the importance of cytopathologist familiarity with this entity so as not to erroneously diagnose a leukemic process. This is extremely important since most cases of TMD spontaneously resolve within a few weeks to months and do not require treatment other than supportive measures.