Acute trilineage leukemia with monosomy of chromosome 7 following an acutepromyelocytic leukemia

We describe an 8 year old boy who had received chemotherapy for an acute pr omyelocytic leukemia and developed a secondary leukemia 27 months after the diagnosis of this first malignancy. Blasts cells were positive for cytopla smic markers CD22, CD3 and myeloperoxidase. Cell surface T and myeloid-asso ciated markers were also detected. Cytogenetic study disclosed monosomy 7. The patient achieved complete remission, but relapsed 15 months later with identical immunophenotypic and cytogenetic findings. Three-lineage commitme nt is proved by the expression of specific criteria for myeloid, and lympho id T and B typing. A multipotent immature progenitor must be the target of leukemogenic agents. The prognosis is obviously ominous.