Therapy-related acute myeloid leukemia with KMT2A-SNX9 gene fusion associated with a hyperdiploid karyotype after hemophagocytic lymphohistiocytosis.

Therapy-related acute myeloid leukemia (t-AML) following treatment with topoisomerase-II inhibitors has been increasingly reported. These compounds (e.g. etoposide) promote DNA damage and are associated with KMT2A rearrangements. They are widely used as first-line treatment in hemophagocytic lymphohistiocytosis (HLH). Here we describe a newborn who developed t-AML after HLH treatment. We provide detailed clinical, cytogenetic, and molecular characteristics of this patient, including the identification of a novel gene fusion - KMT2A-SNX9 - in t-AML. Considering the dismal outcome of this case, we discuss the side-effects of etoposide administration during HLH treatment in infants.