RESUMEN
BACKGROUND: Myeloid sarcoma is a solid tumor that consists of immature myeloid cells occurring at an extramedullary site. It can present before, concurrent with, or after the diagnosis of acute myeloid leukemia or other myeloproliferative diseases, and a proportion of patients never develop bone marrow infiltration. Only a few isolated cases of pediatric orbital myeloid sarcoma have been reported, and they are often associated with a high misdiagnosis rate. CASE REPORT: We report a rare case of pediatric orbital myeloid sarcoma associated with blunt trauma in a 3-year-old Caucasian male patient, which was clinically and radiologically misdiagnosed for orbital subperiostal hematoma. The patient underwent a surgical intervention to drain the hematoma when an orbital mass was found. The microscopic, immunologic, and genetic features of the tumor and the myelogram were in favor of LAM2, and the patient was started with chemotherapy with a favorable evolution within 18 months follow-up. CONCLUSION: Orbital myeloid sarcoma usually exhibits clinical and radiological features that can be easily misleading, especially if it happens de novo or as the first manifestation of acute myeloid leukemia. Only a few isolated cases have reported and proposed trauma as a trigger event of the onset of this type of tumor proliferation, but further investigations and evidence are needed to support this hypothesis.