Cavernous sinus dermoid cyst in uncommun parapharyngeal development

We report a case of dermoid cyst arising in the cavernous sinus and parapha ryngium areas through the foramen lacerum. A 12-year-old girl was hospitali zed in October 1966 for progressive intracranial hypertension. CT before a prior surgical intervention in 1994 showed an intracranial process suggesti ng a dermoid cyst. CT performed in October 1996 showed a temporal process a t the left side measuring 8 cm x 5 cm and well circumscribed with a thin wa ll. This process extended towards the parapharyngium area through the foram en lacerum. The exocranial part measured 4 cm in diameter. The density of t he process strongly suggested a mature dermoid cyst with fatty and calcium components. The histology study confirmed the diagnosis of dermoid cyst. Th e 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 intracr anial tumors occuring 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.