[Atypical presentation of a dermoid cyst with porencephaly]

We report a case of a dermoid cyst in the parasellar area associated with porencephaly. A 22-year-old man presented with headache and visual disturbance. Non-enhanced brain CT showed a high density mass in the parasellar area and a low density area in the left temporal lobe. On gadolinium-enhanced T1-weighted images, a partial rim enhancement was present in the parasellar region. A presumptive diagnosis of Rathke cleft cyst, craniopharyngioma, non-function pituitary adenoma, or germ cell tumor was considered. A left frontotemporal craniotomy was performed and the tumor was removed almost totally. The tumor was well-capsulated and contained whitish, milky debris. The histologic diagnosis was dermoid cyst. The temporal lobe lesion was porencephaly. The postoperative course was uneventful. Their most typical aspect is the presence of a low-density mass on CT, allowing an easy radiologic diagnosis of dermoid cyst containing lipids. Enhancement following contrast administration is uncommon. The hyperdensity may be related to the high protein content of the lesion. The hyperdense aspect of the lesion on CT, and the presence of rim enhancement made the radiologic diagnosis of a dermoid cyst difficult in this case. A case of dermoid cyst associated with porencephaly has not yet been reported in the literature.