Orbital Myeloid Sarcoma: An Initial Presentation of Acute Myeloid Leukemia With Maturation.

Acute myeloid leukemia (AML) is predominantly an adult disease, with significantly lower incidence in children. Myeloid sarcoma (MS), an extramedullary manifestation of AML, can occur in various tissues, though it is exceptionally rare in the orbit. The variable nature of MS complicates its diagnosis and treatment. In this report, we present the case of an eight-year-old boy who exhibited bilateral proptosis and an orbital mass. Initial investigations revealed thrombocytopenia and leukopenia. Imaging tests confirmed an expansive retroorbital lesion. Immunohistochemistry demonstrated positivity for CD34, CD117, and myeloperoxidase (MPO). The mass was ultimately diagnosed as MS. Subsequent bone marrow analysis confirmed AML. This case highlights that MS, although rare, can serve as an initial presentation of AML in pediatric patients. Epidemiology, diagnosis, treatment, and prognosis for MS were discussed.