C-1 root schwannoma with aggressive lateral mass invasion.

Schwannomas are relatively common, benign tumors that are thought to arise from the nerve sheath cell. Schwannomas of the C1 root are extremely rare and seldom invade lateral masses because they gradually increase in size and can extend through the wide space behind the lateral mass instead of the intervertebral foramen. We present here an unusual case of a benign schwannoma that aggressively invaded the lateral mass of C-1.