Regarding the tumor proliferation rate, a higher Ki67 index was observed here in malignant CMTs and a significant but weak negative correlation was observed between miR-18a gene expression and CMTs with Ki67 < 33.3%, while a significant positive correlation was observed between miR-18a and miR-18b expression and malignant tumors with a higher Ki67 index than benign CMTs. This evidence concerns the gene MKI67 and neoplasm.