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.