Which molecular alteration profile commonly accompanies oligodendroglial differentiation in brain tumors?

• A. BRAF mutation
• B. IDH mutation and 1p/19q codeletion
• C. EGFR amplification
• D. TERT promoter mutation

Answer: (B)

Oligodendroglial differentiation is best signaled by the combination of an IDH mutation and 1p/19q codeletion. The presence of an IDH mutation indicates a glioma with a distinct, often more favorable prognosis, while 1p/19q codeletion is a hallmark feature that specifically defines oligodendrogliomas. Together, they define the oligodendroglial lineage and are central to modern classification and treatment considerations.

BRAF mutation is more typical of pilocytic/pleomorphic pediatric-type glial tumors, not the classic oligodendroglioma profile. EGFR amplification is a hallmark of the glioblastoma subtype, especially IDH-wildtype. TERT promoter mutations occur in several glioma types and are not the defining combination for oligodendroglial differentiation.