A long-term survivor of congenital KMT2A-R B-lymphoblastic leukemia with persistently positive bone marrow MRD and multiple CNS relapses.

Here we describe the case of an infant incidentally diagnosed with congenital KMT2A-rearranged (KMT2A-r) B-cell ALL on Day of Life 4. He received the first dose of intrathecal methotrexate on DOL 5, and induction systemic therapy on DOL 6. He demonstrated morphologic remission at the end of induction but had positive bone marrow.