Extramedullary leukemia in children presenting with proptosis

BACKGROUND: We highlight the orbital manifestations of acute myeloid leukemia and the role of peripheral blood smear in the diagnosis of these cases. A total of 12 patients who presented with proptosis and were subsequently diagnosed to have acute myeloid leukemia based on incision biopsy or peripheral blood smear were included in the study. RESULTS: A retrospective review of all cases of acute myeloid leukemia presenting to the Orbital clinic was performed. The age at presentation, gender, presenting features, duration of symptoms and fundus features were noted. In addition the temporal relationship of the orbital disease to the diagnosis of leukemia, laterality, location of the orbital mass, imaging features and the diagnostic tools used to diagnose leukemia were noted. The median age at presentation was 6 years. The male: female ratio was 0.7:1. None of these patients had been diagnosed earlier as having acute myeloid leukemia. The presenting features included proptosis in all patients, orbital mass in 5 (41.7%), visual symptoms in 2 (16.7%) and subconjunctival hemorrhage in one patient (8.3%). A diagnosis of acute myeloid leukemia was established by incision biopsy in 4 patients, subsequently confirmed by peripheral blood smear testing and bone marrow biopsy in 2 patients which revealed the presence of systemic involvement. Imprint smears of the biopsy identified blasts in 2 of 4 cases. In 8 patients presenting with ocular manifestations, diagnosis was established by peripheral blood smear examination alone which revealed a diagnosis of acute myeloid leukemia. CONCLUSION: A peripheral blood smear should be performed in all cases of sudden onset proptosis or an orbital mass in children and young adults along with an orbital biopsy. It can always be complemented with a bone marrow biopsy especially in cases of aleukemic leukemia or when the blood smear is inconclusive.