A girl developed methemoglobinemia during remission-induction therapy for AML

Abstract

An eight-year-old girl was diagnosed as having acute myeloid leukemia (FAB M4), and induction therapy with cytarabine, mitoxantrone, and etoposide was started. On Day 21 of induction therapy, sudden facial pallor and decreased oxygen saturation (SpO₂) were observed. Venous blood gas analysis showed that the methemoglobin (MetHb) level was critically elevated at 54.7%, but no symptoms such as cyanosis or disturbance of consciousness were evident. The MetHb level improved after oxygen administration and erythrocyte transfusion. The cause was identified as ethyl aminobenzoate (Gingicaine Gel 20%^®) used as a topical oral anesthetic in dental and oral surgery, with the presence of febrile neutropenia, which further contributed to the high MetHb level. Methemoglobinemia should be considered in the differential diagnosis for a decrease in SpO₂ of unknown origin.