MRI of epidermoid cyst of the conus medullaris

STUDY DESIGN: A case report of an epidermoid cyst in the conus medullaris with characteristic magnetic resonance imaging (MRI) findings. OBJECTIVE: To describe an epidermoid cyst in the conus medullaris with characteristic MRI findings and point out these findings that correlated well with histologic findings. SETTING: Taiwan. CASE REPORT: A 49-year-old man who suffered from pain and weakness in his right leg for 16 years. MRI showed a heterogeneous signal mass in the conus medullaris. The hyperintense signal area within the lesion may be attributed to the keratin content, whereas the hypointense signal area was related to calcification and soft-tissue component. The histologic findings were compatible with an epidermoid cyst. CONCLUSION: Epidermoid cysts in the conus medullaris must be considered in the differential diagnosis of mass lesions with long duration of related symptoms. The characteristic MRI findings are useful to differentiate epidermoid cysts from other tumors.