Bilateral breast myeloid sarcoma revealing acute myeloid leukaemia in an adolescent female: a diagnostic pitfall

Background Acute myeloid leukaemia may rarely present with extramedullary disease before systemic haematological manifestations, leading to diagnostic delay. Breast involvement by myeloid sarcoma is uncommon and may mimic primary breast pathology. Case report A 15-year-old female presented with rapidly progressive bilateral ulcerative breast masses. Initial evaluation suggested infective or malignant breast disease and empirical therapy was initiated without improvement. Further evaluation revealed haematological abnormalities and imaging demonstrated bilateral infiltrative lesions. Histopathology and Immunohistochemistry demonstrated positivity for MPO and CD117 with negative CD3 and PAX5, supporting myeloid lineage and excluding lymphoblastic lymphoma and bone marrow examination confirmed acute myeloid leukaemia. Clinical improvement with regression of breast lesions was observed following induction chemotherapy. Conclusion Atypical or bilateral breast masses should prompt evaluation for hematologic malignancy to avoid delay in appropriate management.