Future studies are required to define the biologic nature of the subset of meningiomas with loss of p16 expression by immunohistochemistry but an absence of identifiable I CDKN2A i gene alterations. In summary, we demonstrate meningiomas harboring I CDKN2A i homozygous deletion or truncating mutation exhibit loss of p16 expression by immunohistochemistry. Among 12 histologically grade 3 tumors, seven demonstrated loss of p16 expression, of which six harbored I CDKN2A i homozygous deletion and one harbored a truncating mutation in I CDKN2A i (p.A60fs). [Extracted from the article]