Chronic Leukemia of Childhood

Abstract

The chronic leukemias of childhood include chronic myelogenous leukemia (CML) and chronic lymphocytic leukemia. Chronic lymphocytic leukemia in childhood is a monoclonal B-cell neoplasm of great infrequency. CML occurs with enough frequency to warrant a review for the general pediatrician. CML is a clonal (derived from a single cell line) myeloproliferative disorder that has two major forms in childhood, which, as a group, account for 2% to 5% of the childhood leukemias. "Adult" CML is a classic clonal myeloproliferative disease demonstrating the Philadelphia chromosome (Ph1). Its chronic phase lasts 2 to 3 years, then evolves into an acute phase which terminates in the blastic crisis. "Juvenile" CML is more often seen in infants and toddlers and is notable for the presence of rash, adenopathy, absence of the Ph1 chromosome, and elevated level of hemoglobin F. In fact, the two diseases have less in common than the similar names would imply. Approximately one third of CML in childhood is of the juvenile type. A third type of myeloproliferative disorder resembling CML has been reported in two pairs of infant siblings. It clinically resembles juvenile CML, but does not appear to have the nearly universally fatal outcome. Finally, a familial myeloproliferative syndrome, which most closely resembles adult CML, has been reported in a large kindred.