Intradural dermoid cyst located on the ventral surface of the brainstem in a child

Dermoid cysts are very rare neoplasms in the CNS. The unusual neuroimaging signs and surgical treatment of the tumor are concerned in this case report.

A 9-year-old boy complained of slight headache for 2 months, but complete physical examination showed no neurologic deficits on his admission. Computed tomographic scan showed a huge mass with some calcified plaques in the space between the brainstem and the clivus, and the mass was isointense on MR T1-weighted images but hyperintense on T2-weighted sequences. Partial rim enhancement could be found in the superior part of the mass on contrast MR images. The mass was iso- to hypointense on DWI and hyperintense on FLAIR images. A right retrosigmoid approach craniotomy was performed, and the mass was subtotally removed. Pathologic findings indicated that the lesion was a DC with calcification.

The clinical particularities of our case were the deep location and the unusual signs of neuroimaging. New special MR techniques such as DWI and FLAIR can provide more information about the tumor. Surgery is the only effective treatment to this lesion, and total removal is the surgical goal, but subtotal excision also is a wise choice when total removal is very difficult.