A Lateral Neck Myeloid Sarcoma Presenting as Acute Otitis Externa.

Myeloid sarcoma (MS) is a solid extra-medullary tumor of immature myeloid cells which could occur before, during or after remission of acute leukemia at any site on the body. Owing to variation in differential diagnosis, pathologic evaluation and immunohistochemical staining are essential for definitive diagnosis. Rarely, MS has been shown as an isolated extramedullary relapse (iEMR) after allogeneic stem cell transplantation (allo-SCT), which often does not necessarily result in bone marrow involvement. It seems that despite chemotherapy and graft-versus-leukemia (GVL) effects on bone marrow, leukemic cells could remain alive in the extra-medullary region. However, in order to achieve longer survival, timely diagnosis as well as combined systemic, local, and cellular therapeutic modalities should be considered in any patient with iEMR after allo-SCT. We report a left lateral neck isolated MS presented as acute otitis externa in a patient with prior allo-SCT due to acute myeloid leukemia (AML). Therefore, MS should be considered in patients with any history of acute leukemia even if the patient presents with signs and symptoms of an infectious disease.