IMMUNOLOGICAL SUBTYPES OF CHILDHOOD ACUTE LYMPHOBLASTIC-LEUKEMIA IN BULGARIA

With regards to the geographical variation in acute lymphoblastic leuk emia (ALL) distribution, we present data from the immunophenotyping of 171 newly diagnosed cases of childhood ALL in Bulgaria during a 4 yea r period (1990-1994). On the basis of 17 phenotypic markers the distri bution of immunological subtypes was as follows: AUL 4%; Pro-B ALL 13% ; common ALL 42%; Pre-B ALL 11%; B-ALL 1%; T-ALL 28% and unclassified 2%. Most of the cases were between 2 and 5 years of age. Common ALL wa s predominant (53%) in this age group. The male:female ratio was 1.7:1 . The frequency of T-ALL (28%) was significantly higher (P<0.01; t=3.4 9) in comparison to that reported for the U.S.A. and West European cou ntries (mean 13%). It was close to the frequency reported by some auth ors for France (20%), Greece (26%) and south Italy (28.1%). These coun tries and Bulgaria might form an environmental area with a moderate fr equency of T-ALL.