[Congenital leukaemia and transient myeloproliferative disorder: diagnostic difficulties--case reports].

Congenital leukaemia occurs in only 0.8% of all cases of leukaemia in children. Despite great progress in the treatment of childhood leukaemia, prognosis is still poor. This type of leukaemia must be distinguished from leukaemic reactions and transient myeloproliferative disorder. Transient myeloproliferative disorder is a rare condition in the neonatal period, connected with trisomy or other abnormalities of chromosome 21. It is characterized by high blastosis in peripheral blood and bone marrow and it usually resolves without specific therapy in 1 to 3 months. We present two cases: congenital leukaemia and transient myeloproliferative disorder. The first patient was a boy in whom congenital myelomonoblastic leukaemia (M4 in FAB classification) was diagnosed at age of 6 weeks. He was treated according to BFM-96 for acute myeloblasts leukaemia protocol, but there was no remission and he died of progressive congenital leukaemia after 4 months. The second patient was a female neonate with Down's syndrome and a cardiac defect (common atrioventricular canal) in whom hyperleukocytosis with blastosis in peripheral blood and bone marrow were detected at 2 days of age. Although no specific antileukaemic therapy was given her condition improved. At age of 3 months we observed normalisation of peripheral blood and at 5 months of age the bone marrow smear was normal. These cases confirm the difficulties in differentiation between congenital leukaemia and transient myeloproliferative disorder presented in literature. In spite of the same haematological symptoms the only difference may be detection of nonhematopoietic tissue infiltration (skin and central nervous system) commonly occurring in congenital leukaemia or the presence of trisomy and other abnormalities of chromosome 21 in transient myeloproliferative disorder.