Allogeneic Hematopoietic Stem Cell Transplantation as Treatment for Primary Granulocytic Sarcoma of the Breast.

Primary granulocytic sarcoma (GS) is an uncommon, extramedullary proliferation of myeloid cells, occurring in the absence of antecedent myeloproliferative disorder. Breast involvement is uncommon. A diagnosis of GS portends a poor prognosis. Even with intensive chemotherapy for AML, progression to overt leukemia can be delayed for 2-3 years. We, report a 29-year-old man who presented with a painless, left breast lump. A modified radical mastectomy followed by histopathological and immunohistochemical testing confirmed a granulocytic sarcoma. There was no evidence of a concurrent leukemia. Intensive chemotherapy for acute myelogenous leukemia was instituted. Allogenic hematopoietic stem cell transplantation was successfully given. The patient remains in complete remission at follow-up. We highlight the importance of timely diagnosis of this uncommon entity with institution of intensive therapy. Early use of allogenic bone marrow transplantation in the treatment of primary GS may be warranted.