Granulocytic sarcoma 12 years following allogeneic marrow transplant for AML.

Granulocytic sarcoma, a localized extramedullary tumor composed of myeloid blasts, develops in 2–6% of patients at the time of newly diagnosed acute myeloid leukemia (AML).1,2 Granulocytic sarcoma relapse following an allogeneic stem-cell transplant (SCT) is associated with marrow relapse in 20% of patients.2 Isolated granulocytic sarcoma following an allogeneic transplant is rare, seen in only 0.7% of patients and generally observed between 4 and 56 months after transplant, with 56 months being the longest reported duration from transplant to relapse.3 Unfortunately, the majority of patients previously treated with an allogeneic SCT who relapse with an isolated granulocytic sarcoma do poorly, with a median survival of only 10 months.3 Death is often related to progressive AML. Isolated granulocytic sarcoma relapse after an allogeneic SCT generally precedes marrow relapse in 95% of patients, with systemic relapse occurring within 12 months.4