Lineage switch from acute lymphoblastic leukemia to myeloid leukemia

Objective and background Acute lymphoblastic leukemia (ALL) is the most common pediatric malignancy, representing 25% of childhood cancers, with a peak prevalence between 2 and 9 years. Conversions of the leukemic cell lineage throughout the duration of the disease is a rare manifestation, accounting for 6–9% of relapsed cases and being more frequently observed in pediatric patients. We present a case of a patient with a lineage switch from lymphoblastic leukemia to myeloid leukemia. Case presentation A 60-year-old male was seen due to pancytopenia, weight loss and weakness. Initial laboratory work-up was performed. Bone and marrow aspirate flow cytometric analysis disclosed pre-B lymphoblastic acute leukemia BCR ABL (−), 46 XY, hyperdiploid, CD20(−), CD 10 (−), CD19 (+), CD33 (−), CD34 (+), CD38 (+), CD79a (+), TdT (+), IgS(−), CD45 (+/−), HLA-DR (+), MLL (−), FLT3 (−), TEL AML (−). He was treated with a pediatric-inspired TOTAL XI schedule. Sixty days afterward, induction blasts appeared in the peripheral blood, but immunophenotyping was not conclusive for MRD+ status. One week later, he presented blasts in the peripheral blood compatible with acute myeloid leukemia. CD7 (+−), CD13 (+), CD14 (−), CD15(−), CD33(+), CD34(+), CD38(+), CD45(+−), CD64(−), CD117(+), HLA-DR heterogenous. BCR-ABL, PML-RAR alfa, and FLT-3 were repeated in peripheral blood when AML developed and was negative. The patient started subcutaneous cytarabine and was alive 90 days after initial diagnosis with active AML leukemia. Conclusion There is a small number of reports of lineage conversion in the literature, probably because immunophenotyping is performed at diagnosis without a follow up.