Symptomatic syringomyelia associated with a dermoid tumor in the posterior fossa.

A 28-year-old female presented with a dermoid tumor in the posterior fossa associated with symptomatic syringomyelia. Magnetic resonance (MR) imaging revealed cervical syringomyelia and tonsillar herniation concomitant with an intradural posterior fossa tumor which was totally removed. The histological diagnosis was dermoid tumor. Her symptoms subsided and MR imaging demonstrated complete resolution of the syrinx 12 months after tumor removal. Benign congenital intracranial tumor may cause tonsillar herniation resulting in symptomatic cervical syringomyelia. However, both tonsillar herniation and cervical syrinx may clinically and radiologically resolve following removal of the intracranial lesion and posterior fossa decompression.