Granulocytic sarcoma is an uncommon manifestation of myelogenous leukemias in which focal masses of immature myeloid cells from the granulocytic lineage infiltrate bone and soft tissue. It is most common in the pediatric population and may present at any time in the course of the disease, either concurrently with the onset of leukemia or during a remission or relapse. Occasionally, it may precede the clinical onset of acute myelogenous leukemia (AML), presenting a diagnostic challenge.