Rare Intradural Cervical Nerve Root Metastasis of Follicular Thyroid Carcinoma.

Intradural extramedullary nerve root metastasis is extremely unusual with only a handful of cases reported, and it presents most commonly in the thoracic and lumbosacral regions. We report the first case of metastasis to a ventral cervical nerve root in a patient with low-grade follicular thyroid carcinoma thought to be in remission for several years. Histopathology demonstrated malignant transformation and invasion of the nerve root. This case underscores that any history of malignancy regardless of staging, grading, or remission status should raise the suspicion of metastasis as it can mimic other spine and nerve sheath tumors and represent malignant transformation. Gross total resection can be safely achieved with intraoperative neuromonitoring and result in improved function; however, treatment is likely palliative.