Figure.

(A) Magnetic resonance imaging (MRI) of the cervical spine performed two days after the symptom onset. Sagittal T2-weighted imaging (T2WI) shows spinal cord compression at the C5/6 level, but the lesion causing the left C8 and T1 level palsy remains undiagnosed. The asterisk indicates the T1 vertebral body in A to C. (B, C) Coronal short-tau inversion recovery (STIR) imaging reveals multinodular lesions (arrows) along the enlarged left C8 nerve root. (D) Axial T2WI. The arrow indicates thickening of the left C8 nerve root. (E) Axial T1-weighted imaging (T1WI). The arrow indicates thickening of the left C8 nerve root. (F) STIR imaging clearly delineates the cervical nerve lesion. (G) Axial fat-saturated T1WI with gadolinium enhancement. The cervical nerve lesion shows heterogeneous enhancement. (H) The lesion protruding upward from the cervical nerve (B, arrow) is resected and histologically evaluated. An admixture of a more cellular area comprising spindle-shaped cells (Antoni A pattern, right side) and a hypocellular, looser area (Antoni B pattern, left side) is observed [Hematoxylin and Eosin (H&E) staining, ×200]. The Antoni A pattern is dominant. (I) Hyalinized vessels and palisading of the nuclei are observed (H&E staining, ×200). (J) Diffuse immunoactivity against S100 protein is observed (×200). (K) MIB1 is scarcely immunopositive, and the labeling index is 1-2% (×200).