Band-like marginal gingival necrosis as the initial manifestation of acute monocytic leukemia: a case report

Abstract

Oral manifestations may precede the diagnosis of acute myeloid leukemia (AML), particularly in monocytic subtypes, but the typical findings are gingival enlargement, spontaneous bleeding, petechiae, or nonspecific ulceration. Band-like necrosis confined to the gingival margins and interdental papillae as the first clinical clue is unusual and may be misinterpreted as a local necrotizing periodontal or infectious lesion. A previously healthy 29-year-old woman presented with gingival swelling and pain for 1 month, followed by low-grade fever and fatigue for 1 week. Oral examination revealed generalized erythematous gingival swelling with band-like gray-white necrosis involving the gingival margins and interdental papillae in the bilateral posterior regions of both jaws, accompanied by punctate bleeding and tenderness. The initial complete blood count showed marked leukocytosis (134.35×10^9/L), anemia (hemoglobin, 100 g/L), thrombocytopenia (49×10^9/L), and abnormal white cells accounting for 83%, while C-reactive protein was not elevated (4.41 mg/L), prompting urgent hematology referral. Bone marrow morphology, histology, and flow cytometric immunophenotyping supported a diagnosis of acute monocytic leukemia with monocytic differentiation (AML-M5b). The patient received transfusion support, anti-infective therapy, and idarubicin plus cytarabine induction chemotherapy. Gingival swelling and necrotic lesions improved markedly within 1 week. At 5-month follow-up, peripheral blood counts had recovered, bone marrow morphology was consistent with complete remission, measurable residual disease testing detected no abnormal myeloid blasts (<0.01%), and KMT2A::AFDN was undetectable by quantitative PCR. At the last available follow-up in May 2025, no recurrence of gingival swelling or necrosis was observed after subsequent hematopoietic stem cell transplantation. Band-like marginal gingival necrosis may be a rare initial oral manifestation of acute monocytic leukemia and should not be attributed automatically to local periodontal infection, particularly when systemic symptoms or spontaneous bleeding are present. Early complete blood count testing and prompt hematology referral are essential for avoiding diagnostic delay in patients with necrotizing gingival lesions.