Fig 2.

Patient 1. Axial T2 FLAIR (A) MR image demonstrates abnormal T2 FLAIR signal in the right lateral pons extending into the right trigeminal nerve (arrow marks the site of biopsy, arrowhead marks the normal left trigeminal nerve). B, Multivoxel MR spectroscopy demonstrates increased choline relative to NAA in the right-sided voxel corresponding to the tumor (arrow). C, Operative photograph shows a right retrosigmoid approach to the expanded right trigeminal nerve (arrow), with biopsy being obtained (courtesy of Jonathan D. Breshears, MD). D, Hematoxylin-eosin stained histology slide (original magnification ×20) demonstrates an infiltrative astrocytic neoplasm with nuclear pleomorphism, brisk mitotic activity, microvascular proliferation (arrow), and pseudopalisading necrosis (arrowhead). Pathologic diagnosis was a glioblastoma, WHO grade IV. No peripheral nerve was identified in the specimen despite the biopsy location, likely reflecting the origin from glial cells in the trigeminal root entry zone.