Orbital indeterminate cell histiocytosis

An 8-year-old female presented to the oculoplastics clinic with 3 months of left upper eyelid fullness and edema. Examination showed a mass in the left anterior superior orbit with erythema. Imaging demonstrated a well-circumscribed superolateral orbital mass that was T1 hypointense and T2 hypo-to-iso intense with contrast enhancement. An incisional biopsy was performed via an upper lid crease incision. Histopathology showed aggregates of histiocytic cells with fibrosis and infiltration of eosinophils. Immunohistochemistry revealed positive CD68 and CD163 staining and negative langerin staining, confirming the diagnosis of indeterminate cell histiocytosis. There was no systemic involvement or associated dermatologic findings. Repeat exam 3 months later showed no change in the size of the lesion and the patient was referred to hematology-oncology for treatment. On most recent exam, the patient had no new symptoms or side effects following 3 months of oral hydroxyurea (25 mg/kg/day). Repeat orbital imaging showed no progression of the lesion and the patient will be monitored closely. Here, we report a rare case of isolated orbital indeterminate cell histiocytosis in a young child.