Fig 3.

Patient 3. Axial T2 FLAIR (A), coronal T2 FLAIR (B), and coronal postgadolinium T1 (C) MR images demonstrate abnormal T2 FLAIR signal in the left lateral pons extending into the expanded left trigeminal nerve (arrow), with enhancement shown at the root entry zone (C). The arrowhead marks the normal right trigeminal nerve, and the asterisk marks the approximate site of biopsy in the pons. D, Hematoxylin-eosin stained histology slide (original magnification ×40) demonstrates an infiltrating population of neoplastic astrocytes with irregular ovoid nuclei (arrow) and coarse chromatin and scant eosinophilic cytoplasm. No mitotic activity, microvascular proliferation, or foci of necrosis are present. The pathologic diagnosis was a diffuse astrocytoma, WHO grade II.