The patient went on to have a resection. 

Histology

MICROSCOPIC DESCRIPTION:

Sections show a moderately cellular tumor demonstrating focal rosette formation and solid sheet-like growth. Tumor cells contain scant cytoplasm, oval granular nuclei and inconspicuous nucleoli. No mitoses, necrosis or microvascular proliferation are seen.

Immunohistochemical results show tumor cells stain: GFAP-, CD117-, Chromogranin- and Synaptophysin+. The Topoisomerase proliferation index is approximately 1-2%.

FINAL DIAGNOSIS: Pineal parenchymal tumor with intermediate differentiation (WHO II).