An eight-year-old boy presented with a one-month history of left eyelid swelling. The patient was diagnosed with periorbital cellulitis at another clinic and was treated with oral antibiotics. However, the swelling did not subside. On initial consultation, the patient had left upper eyelid swelling with erythema. His extraocular muscle motility was normal, and the results of blood tests were unremarkable. A computed tomographic scan demonstrated a mass in the superior orbit with destructive changes in the left frontal bone. Histopathological examinations revealed a dense infiltrate of histiocytic cells. Immunohistochemical staining of the tumors for CD1a and Langerin was positive. A pathological diagnosis of Langerhans cell histiocytosis was made. Since orbital Langerhans cell histiocytosis has a high risk for central nervous system involvement, chemotherapy was the treatment of choice for any residual lesion to prevent sequelae to the central nervous system. At the six-month follow-up, the lesion did not recur, and the patient did not experience any central nervous system sequela.
