A 16-month-old male infant was presented with swelling of the left upper eye lid 4 weeks after a blunt orbital trauma. A prolonged hematoma was suspected and the child was discharged with an appointment 4 weeks later. However, the child was presented again with progressive swelling of the lid 10 days later. Magnetic resonance imaging (MRI) showed a tumor extending from the frontal bone to the anterior cranial fossa and into the orbit. An incisional biopsy led to the diagnosis of orbital Langerhans cell histiocytosis and systemic therapy led to complete remission of the tumor. Prolonged periorbital swelling must always prompt further diagnostics even when patients present with a history of trauma.