Acute monocytic leukemia (FAB M5) involving the placenta associated with delivery of a healthy infant: case report and discussion.

Acute leukemia seldom presents during pregnancy, and though pregnancy may not affect the course of leukemia, fetal complications and maternal mortality are high. Documented placental involvement is rare, as are metastases to the fetus. Comprehensive review of the literature reveals only a few reports of maternal or fetal leukemia with placental involvement. We encountered a case of a 45-year-old woman who presented at 29 weeks' gestation with acute monocytic leukemia with t(9;11). She was managed conservatively. Labor was induced at 33 weeks, with delivery of a healthy male infant prior to induction chemotherapy. The baby remained well at 18 months of age. The placenta showed isolated microinfarcts and an infiltrate in the basal plate of leukemic cells confirmed by immunohistochemistry. No invasion into chorionic villi was seen. Little is known about the biological significance of placental involvement and inherent defense mechanisms of the placenta in maternal cancers. Therefore, detailed histopathologic examination of the placenta should always be performed and reported in leukemic patients, regardless of fetal outcome.