Congenital leukaemia and the neonatal myeloproliferative disorders associated with Down's syndrome.

Congenital leukaemia is a rare disease with approximately 100 cases reported in the literature. It is most often diagnosed as acute myelogenous leukaemia (AML). Leukaemic skin nodules and hepatosplenomegaly are the most frequent clinical findings noted. The laboratory manifestations include a markedly elevated white count with a large percentage of blasts, and a bone marrow aspirate that is cellular with a monotonous population of immature cells. Neonatal leukaemoid and leucoerythroblastic reactions may cause diagnostic confusion. In particular, the neonate with Down's syndrome can manifest either AML or a profound transient myeloproliferative syndrome that is clinically and haematologically indistinguishable from congenital AML. In contrast to congenital leukaemia, however, this myeloproliferative syndrome is transient and resolves spontaneously without anti-leukaemia therapy. On the other hand, untreated congenital leukaemia is a fatal disease. For this reason it is important to establish early diagnosis of congenital leukaemia and institute therapy. Treatment programmes should be modelled after established childhood programmes for acute lymphocytic leukaemia and acute myelogenous leukaemia.