Definition

A rare type of cancer that is made up of myeloblasts (a type of immature white blood cell) and forms outside the bone marrow and blood. The tumor cells may look green when viewed under a microscope. Extramedullary myeloid tumors can occur anywhere in the body. They most commonly occur in people with acute myeloid leukemia or a myeloproliferative disorder. Also called chloroma, granulocytic sarcoma, and myeloid sarcoma.