Unsuspected gastric granulocytic sarcoma in a patient with myelodysplastic syndrome.

Granulocytic sarcoma (GS) is an uncommon and localized extramedullary tumor composed of immature granulocytic cells. Most GS reported in large series were not associated with overt acute myelogenous leukemia. Gastric perforation occurred during prednisolone therapy in a 72-year-old Japanese male with a four-month history of a myelofibrosis-like state.