Acute megakaryoblastic leukemia with RBM15::MKL1 fusion presenting as neonatal acute liver failure: rescued by living-donor liver transplantation.

Acute liver failure in the neonatal period is commonly caused by infections, metabolic disorders, immune disorders, or neonatal hepatitis-like diseases of unknown etiology; however, malignant diseases are rarely included in the differential diagnosis, and leukemia may be overlooked. We report a case of neonatal acute liver failure that required living-donor liver transplantation from the patient's father, which was later diagnosed as acute megakaryoblastic leukemia (AMKL) harboring an RBM15::MKL1 fusion transcript. After liver transplantation, leukemic blasts infiltrated the transplanted liver, necessitating the initiation of chemotherapy. The patient achieved remission and has survived for four years after completion of reduced-intensity AML-type chemotherapy. RBM15::MKL1-positive AMKL is characteristically associated with both myelofibrosis and hepatic fibrosis. Congenital cases have also been reported, suggesting that RBM15::MKL1 AMKL may originate in the intrauterine fetal liver. A literature search for "acute liver failure" and "acute megakaryoblastic leukemia" revealed five cases reported since 2000. All patients had an RBM15::MKL1 fusion transcript and all died. In contrast, survival has been reported in patients with RBM15::MKL1-AMKL who did not present with acute liver failure. We speculate that our patient survived because acute liver failure was successfully managed with living-donor liver transplantation.