Granulocytic sarcoma in breast after bone marrow transplantation.

Granulocytic sarcoma is a localized extramedullary solid tumor composed of immature myeloid cell and is usually associated with acute myeloid leukemia or myelodysplastic syndrome. Although it can involve any site, commonly in lymph nodes, skin, bone and soft tissue, the involvement of breast is unusual. Especially, the involvement of the breast as a pattern of relapse after bone marrow transplantation is extremely rare.