Intraoral myeloid sarcoma presenting as toothache and gingival mass

A female patient in her 70s with a medical history of myelodysplastic neoplasm presented to the outpatient department with a 4-month history of toothache, painful gingival swelling and loose teeth that required extractions. Intraoral examination revealed a swelling in the lower anterior portion of the mandible, which displaced her teeth. Incisional biopsy of the gingival lesion revealed dense aggregates of atypical round cells which stained positive for CD43, CD45, CD33 and myeloperoxidase, consistent with myeloid sarcoma. Subsequent bone marrow biopsy displayed hypercellular marrow with immature myeloid elements and 21% myeloblasts by flow cytometry, compatible with diagnosis of acute myeloid leukaemia (AML). The patient initially went into remission after treatment but later died of AML relapse after 18 months.