[Immunophenotype. Clinical and laboratory features of acute lymphoblastic leukemia in Chile. Study of 500 children and 131 adults].

We describe the clinical features and immunophenotype of 500 children and 131 adults with acute lymphoblastic leukemia (ALL), diagnosed between 1984 and 1993. Cases were classified, according to immunophenotype in B-cell ALL with three subtypes (pro-B or null, common and B) and T-cell ALL. Among children, common ALL accounted for 74% of cases and pro-B all was more common in children of less than one year (14%). B ALL was observed in 2% of children. Ten percent of children, mostly males, had T-cell ALL. The third part of these children had high leukocyte counts and a mediastinal mass. Children from Mapuche origin, compared with Caucasian children had a lower proportion of common ALL (36 and 74% respectively) and a higher proportions of T-cell ALL (41 and 10% respectively). Among adults common ALL was the most common phenotype (72%) followed by T-cell ALL (15%), pro-B ALL (11%) and B-cell ALL (2%). There was a lower incidence of children with common ALL with positive cytoplasmic immunoglobulin compared to North American or European studies (2 and 15-33% respectively) and a higher proportion of adults with common ALL compared with pro-B cell ALL, in contrast to European studies that show a higher proportion of patients with pro-B cell ALL. No other immunophenotypic, clinical or laboratory differences were observed with ALL from developed countries. It is concluded that the immunophenotyping of ALL allows a more precise diagnosis of this disease.