Orbital granulocytic sarcoma: an unusual presentation of acute myelocytic leukemia.

Granulocytic sarcoma is an unusual manifestation of acute myelogenous leukemia in children and presents a diagnostic dilemma when it precedes the development of systemic disease. We present CT and MRI findings of an extraconal mass proven to be granulocytic sarcoma in a 6-year-old otherwise healthy boy with several months' history of worsening unilateral proptosis. This case is unique in providing exquisite CT and MRI correlation and in demonstrating rapid response to therapy. Further, as cytogenetics were positive for the t(8,21) translocation, this case provides opportunity for discussion of the associated incidence of this translocation and concomitant better prognosis.