Figure 7. Diagnostic use of lineage-specific transcription factor “code” in evaluation of a glioblastoma of the pineal region.

Examination of H&E stained sections of a pineal tumor reveals high-grade histologic features somewhat suggestive of glioblastoma (A). Immunohistochemistry showed nuclear CRX in normal pineocytes (red arrow) that are infiltrated by the invasive tumor which is negative for CRX (black arrow) (B). The germ cell marker OCT4 is absent in neoplastic cells and in pineocytes (C). However, robust expression of OLIG2 is evident in neoplastic cells but absent in infiltrated pineocytes (arrow) (D). Original magnification 400x.