[A case of myeloid sarcoma in the anterior mediastinum].

We report a case of myeloid sarcoma in the anterior mediastinum. The patient was a 33-year-old man with a chief complaint of right shoulder pain, right upper limb edema, and cough. Chest contrast-enhanced computed tomography (CT) revealed a partially enhanced anterior mediastinal tumor. A CT-guided biopsy was then performed, and a Hematoxylin-eosin (HE) stain revealed mitosis of tumor cells and other cells, including eosinophils. Immunohistochemical stains with myeloperoxidase, CD34, CD43, CD68 and c-Kit tests were positive for tumor cells. Due to a pathological diagnosis of myeloid sarcoma, he was treated with chemotherapy based on a diagnosis of acute myelogenous leukemia. After complete remission was obtained, the patient visited another hospital to receive an unrelated bone marrow transplantation. Although it rarely occurs as a mediastinal tumor, the prognosis of myeloid sarcoma is unfavorable, and thus should be taken into consideration as a differential diagnosis.