Gilteritinib in an Isolated CNS Recurrence of FLT3-ITD Positive AML.

Central nervous system (CNS) involvement in adult acute myeloid leukemia (AML) is uncommon and more frequently observed at relapse than at initial presentation. Typically, CNS relapse coincides with systemic disease, evidenced by detectable blasts in the bone marrow (BM) and/or peripheral blood. We describe a rare case of an 82-year-old patient with a history of AML, diagnosed three and a half years earlier, who developed an isolated CNS relapse while receiving palliative chemotherapy-without concurrent BM involvement or molecular evidence of systemic progression. Cerebrospinal fluid (CSF) analysis revealed blast cells harboring an FLT3 internal tandem duplication (FLT3-ITD). Targeted therapy with an FLT3 tyrosine kinase inhibitor (TKI) achieved complete remission, with clearance of FLT3-ITD from the CSF.