Abnormal Circulating Leukaemia-like Megakaryoblasts In The Placenta Of A Stillborn: Congenital Leukaemia (CL) Transient Abnormal Myelopoiesis (TAM)

Introduction: The preleukaemic and leukaemic diseases of infant and early childhood have been described. CL is a rare haematologic disease most often diagnosed at birth or within the first month of life and commonly are of acute myeloid leukaemias (AML). This however need to be differentiated from TAM of the newborn. We present a case and highlight challenges encountered in placental examination. Case report: A 35-year-old lady, in her fifth pregnancy presented at 40 weeks of gestation with absence in fetal movement. Further investigation confirmed an intrauterine death. Following induction of labour a male macerated stillborn was delivered. It was observed that the umbilical cord was short and the right testis was undescended. There were no associated syndromic features seen. The parents did not consent to a postmortem examination. The placenta was pale, foul smelling with meconium stains. Microscopically, there were numerous circulating immature precursors and nucleated red blood cells within the fetal vessels in the umbilical cord and chorionic villi. The morphology and immunohistochemistry were suggestive of a megakaryoblastic lineage. Discussion: Both AML and TAM are known manifestations in neonates with Down’s syndrome, predominantly involving the megakaryoblastic series. Although clinically and haematologically indistinguishable, TAM is transient and usually exhibits a spontaneous regression. However, with heart and liver involvement TAM may cause fetal demise. The underlying genetic contributions were not established in this case. However, both entities along with other neonatal leukaemoid and leucoerythroblastic conditions need to be considered. Hence detailed placental examination with relevant immunohistochemistry analysis is recommended.