This notwithstanding, our results agree with what previously reported, as CD13 was significantly less expressed in anaplastic meningiomas (68%) than in benign (99%) and atypical ones (95%); furthermore, the positivity detected within the anaplastic meningiomas’ group was much more often of weak type than in the other groups, involving a minority of tumor cells. The gene discussed is ANPEP; the disease is anaplastic meningioma.