[Cavernous sinus dermoid cyst with unusual parapharyngeal development].

We report a case of dermoid cyst arising in the cavernous sinus and parapharyngium areas through the foramen lacerum. A 12-year-old girl was hospitalized in October 1966 for progressive intracranial hypertension. CT before a prior surgical intervention in 1994 showed an intracranial process suggesting a dermoid cyst. CT performed in October 1996 showed a temporal process at the left side measuring 8 cm x 5 cm and well circumscribed with a thin wall. This process extended towards the parapharyngium area through the foramen lacerum. The exocranial part measured 4 cm in diameter. The density of the process strongly suggested a mature dermoid cyst with fatty and calcium components. The histology study confirmed the diagnosis of dermoid cyst. The frequency of intracranial dermoid cysts is 2 to 3 times less than that of epidermoid cysts. This is an uncommon process accounting for 1% of intracranial tumors occurring in children. In the sustentorial spaces, the process occurs more frequently in the parasellar area. To our knowledge, exocranial extension has not been reported to date.