Epilepsy caused by an unrecognized pencil lead misdiagnosed as intracerebral cavernous malformation.

Transorbital penetrating injury is relatively uncommon following head trauma, and delayed onset of neurological complications due to retained intracerebral foreign bodies has rarely been reported. We describe the first child case of late-onset epilepsy caused by an accidental transorbital penetrating injury, resulting in a retained pencil lead fragment that was mistaken for cavernous malformation. A 14-year-old girl presented with abrupt onset of nocturnal bilateral tonic seizures. The patient was previously healthy and denied any head trauma. The seizures were not well controlled by antiepileptic drugs. Right frontal lobe epilepsy due to a cavernous malformation was suspected on the basis of brain magnetic resonance imaging and electroencephalography findings. A planned operation unexpectedly revealed the intracerebral pencil lead. This foreign body had gone undetected for 11 years following a minor transorbital penetrating injury. The patient remained seizure-free during the 1-year post-operative follow-up period. Head trauma by a pencil can cause transorbital penetrating injury in children. It is difficult to detect retained small foreign body fragments and the clinical presentation can be delayed. It may be mistakenly diagnosed as other pathologies, especially when patients deny any history of head trauma.