A giant dermoid cyst of the orbit present in adulthood — a case report

Dermoid cysts are common orbital developmental tumors in childhood. They account for 3 to 9% of primary orbital tumors. They are considered to be congenital, but not all of them are diagnosed at birth. Dermoid cysts are benign choristomas that arise from sequestration of ectoderm along the lines of embryonic fusion of mesodermal processes destined to be bone. In most cases, the lesion is close to the zygomatic-frontal suture leading to a superotemporal subcutaneous mass in the eyebrow or eyelid. The intraorbital location is relatively rare and more prone to complications, particularly compressive. We report the case of a 41-year-old man with a large intraorbital tumor. The imaging aspects were evocative of an extraconal dermoid cyst. The tumor was resected through a transconjunctival route. Histopathologic examination confirmed the diagnosis of dermoid cyst.