Extramedullary myeloid leukemia: the value of cytogenetic analysis in pediatric orbital tumors.

Orbital extramedullary myeloid tumor, or granulocytic sarcoma, can be difficult to diagnose even with the use immunohistochemical stains, especially if it precedes the development of systemic leukemia. We describe a 6-year-old boy with a rapidly progressive orbital tumor. This patient underwent an orbital biopsy, which was consistent with extramedullary myeloid tumor but not conclusive. Cytogenetic studies on a bone marrow biopsy revealed a translocation consistent with acute myelogenous leukemia.