PRENATAL-DIAGNOSIS OF A TRANSIENT MYELOPROLIFERATIVE DISORDER IN TRISOMY-21

We report the prenatal diagnosis of a transient myeloproliferative dis order suggestive of leukaemia in a fetus with hepatosplenomegaly, hydr ops and 47, XY,+21 karyotype. The initial fetal white blood cell count at 26+5 weeks' gestation was 190/nl with 70 per cent blast cells. Imm unophenotyping of the large blasts revealed surface markers suggestive of an early stem cell differentiation arrest resulting in undifferent iated polyclonal myelopoiesis. The fetal heart tracing showed minimal beat-to-beat variability in the presence of high leukocyte counts. Ser ial fetal blood sampling showed decreasing blast cells in the peripher al blood and normalization of white blood cell counts. Although there was increasing hydrops, this period was marked by improvement of the f etal heart rate pattern. Finally the fetus developed pancytopenia with increasing hydrops, AV-valvular insufficiency and venous Doppler stud ies indicative of cardiac decompensation prior to intra-uterine death at 31+5 weeks' gestation. Post-mortem examination revealed marked live r and splenic necrosis without evidence of residual leukaemic infiltra tion in any organ. Fetal hydrops and hepatosplenomegaly may indicate a n underlying haematopoietic disorder warranting further investigation. Furthermore, this case indicates that transient abnormal myelopoesis may result in a fulminant clinical picture much like true leukaemia. T his may be due to increased vulnerability of the fetus or represent a disease mechanism unique to fetuses with chromosomal abnormalities. (C ) 1998 John Wiley & Sons, Ltd.