Congenital leukemoid reaction followed by fatal leukemia. A case with Down's syndrome.

A serial clinical, hematologic, and cytogenetic study was done on a baby with Down's syndrome in whom a myeloid leukemoid reaction developed at birth that spontaneously regressed within a month only to relapse two years later to an acute undifferentiated stem cell leukemia. He died 1 1/2 months after onset. The unresolved controversy of the diagnosis of the congenital leukemia-like state is discussed. The importance of following up such patients with apparent remission of their congenital leukemia-like disorder is emphasized.