Abstract
Acute leukemias are often of myeloid or lymphoid origin. However, some acute leukemias revealed an undefined differentiation into a single lineage. Mixed phenotype acute leukemia (MPAL) is an uncommon diagnosis were blasts can share B/T/myeloid phenotype. Here, we report a rare case of a 17-year-old Moroccan female diagnosed with B/T mixed phenotype acute leukemia and a high hyperdiploid karyotype who relapsed after one year of complete remission with a lineage switch to B-cell acute lymphoblastic leukemia. This case report corroborates the disclosed findings about the high occurence of abnormal karyotypes and poor prognosis of MPAL.