MKI67 and pituitary tumor: With the Ki-67 index alone being insufficient to predict tumor behavior, the mitotic count usually low in pituitary tumor and the method of quantification of p53 not well reproducible in all laboratories, a tumor was considered as proliferative if at least two of the three markers (Ki-67 ≥ 3%, mitotic count > 2/10HPF and p53 positive) were present.