[Acute lymphoblastic leukemia with L1 morphology arising during treatment for ALL-L3 in a child with AIDS].

A child with AIDS is presented who developed L1-ALL while being treated for L3-AL. After achievement of complete remission of the former, he suffered a relapse with L3 morphology. Although the possibilities of a shift in both the morphology and the immunophenotype of ALL in relapse are well known, the rarity of L1-ALL in association with AIDS is stressed by the authors, along with the factors related with the morphologic and phenotypic changes shown by these patients.