[Intraorbital conjunctival cyst after a penetrating orbital injury: a case report]

We report a case of intraorbital conjunctival cyst following a penetrating orbitocranial injury. The patient was a 28-year-old male who was hospitalized with exophthalmos, retrobulbar pain and upper gaze disturbance of his left eye. When he was 4 years old, a thin iron rod had penetrated intracranially through the inner angle of his left orbit. He was hospitalized and treated conservatively for about two weeks. The left eye ball was intact and visual acuity was normal, although bloody fluid had continuously flowed out from the left inner angle of the conjunctival wound for a few days. He had been febrile to 39 degrees C and complained of headache for one week. Subsequentry, the symptoms gradually improved through conservative therapy. When he was a junior high school student, he noticed exophthalmos of his left eye. However, he had never been examined closely, until he was 28 years old. We suspect that he had suffered from meningitis caused by the penetrating orbitocranial injury, and had fortunately improved under the conservative therapy. On admission to our hospital, a craniogram showed fracture of the left orbital roof, and coronal and three-dimensional computed tomography (CT) scans clearly demonstrated the orbital fracture. CT revealed a cystic mass in the retrobulbar space, and a porencephalic cyst in the medial basal frontal lobe. On magnetic resonance imaging (MRI) scans, both cysts were of low intensity on T1-weighted imaging, and of high intensity on T2-weighted images. Coronal and sagittal MRI scans showed that the two cysts were connected with each other through the fracture in the orbital roof. We diagnosed therefore that the orbital cyst was a herniated porencephalic cyst of the frontal lobe. Surgery was performed by a transcranial approach. The porencephalic cyst adhered to the fractured lesion of the frontal base but did not extend into the orbita. The intraorbital cyst was totally removed by opening the orbital roof including the fractured lesion. The cyst contained milky fluid. Postoperatively, the exophthalmos, retrobulbar pain and upper gaze disturbance showed gradual improvement. On histological examination, the cyst was found to be lined by non-keratinized stratified squamous epithelium and was diagnosed as a conjunctival cyst. This case was considered to be one of traumatic conjunctival cysts caused by a penetrating orbitocranial injury. Orbital conjunctival cysts have been reported to comprise about 10% of orbital epidermoid and dermoid cysts. Of these cysts, traumatic conjunctival cysts are rare, and only a few cases have been described. The etiology and therapy of orbital conjunctival cysts are discussed.