Zyrelle Avienn A. Santos, M.D.
Objective: Orbital myeloid sarcoma, or chloroma, is a rare extramedullary manifestation of acute myeloid leukemia (AML) in children and may present as unilateral or bilateral proptosis, commonly misdiagnosed as a solid tumor of nonhematologic origin. This paper aims to present a case of AML manifesting as myeloid sarcoma, to discuss the differential diagnoses for the disease, and to determine the appropriate diagnostic methods and treatment regimens. Case: A 3-year-old male was brought to the national children’s hospital (NCH) for right orbital mass. Physical examination revealed a protruded right eyeball with 4x4x2 cm mass on the right upper eyelid pushing the right eye downwards, with greenish discharge, hyperemic sclera and nonreactive right pupil. Cranial CT scan revealed avidly enhancing lobulated right retro-bulbar mass with mild remodeling of the adjacent osseus structure and proptosis of the right eye. Biopsy of the mass revealed round cell neoplasm, differential diagnoses includes: capillary hemangioma of the orbit, rhabdomyosarcoma and orbital lymphoma. Bone marrow aspiration findings were consistent with AML, and flow cytometry showed blasts strongly positive for CD34, HLA-DR, CD13, CD33, and cMPO, suggestive of AML as well. Conventional AML chemotherapy was initiated which resulted in gradual regression of the mass size and close monitoring was advised. Conclusion: This case validates that children presenting with orbital mass warrants a high index of suspicion for AML and requires appropriate and timely diagnostic workup. Early recognition of orbital myeloid sarcoma is often a challenge due to the multitude of differential diagnoses, often leading to high rates of misdiagnosis and late initiation of appropriate management.