MPO and myeloid sarcoma: GS is a kind of solid tumor composed of immature granulocytes, and initially, named Chloroma because of the myeloperoxidase (MPO) in the tumor cells which leads to greenish cut surface.[6] The conception of extramedullary myeloid cell sarcoma (EMT) was mentioned in the year 1988 by Davery, including extramedullary infiltration of leukemia and isolated GS.[7] The latter one is quite rare worldwide, and also known as nonleukemic GS, which means no peripheral blood, or bone marrow involved.