Mediastinal Granulocytic Sarcoma

Abstract

Granulocytic sarcoma (GS), also known as myeloid sarcoma, extramedullary myeloid tumor (EMT), is defined as an extramedullary tumor composed of immature granulocytic precursor cells and initially, named Chloroma because of the myeloperoxidase (MPO) in the tumor cells which leads to greenish cut surface. GS can occur at any site, with skin and lymph node being the most common sites of involvement, and followed by soft tissue, bone, periosteum, epidural structure, and infrequently gastrointestinal tract. The mediastinum and pericardium are unusual sites of manifestations. GS was originally described by Burns in 1811, but it was not until later in 1853, when it was investigated by King who reported it as “a green colored tumor.” In 1966, Rappaport proposed the term “granulocytic sarcoma.” The conception of extramedullary myeloid cell sarcoma (EMT) was mentioned in the year 1988 by Davery, including extramedullary infiltration of leukemia and isolated GS. In 2001, GS was classified as “myeloid sarcoma” in the classification of hematopoietic and lymphatic tumors. It was not until 2002, when the WHO declared the name “myeloid sarcoma.” However, granulocytic sarcoma seems to be the most frequently used term, since around 30% do not show MPO positivity.