According to the latest edition of the World Health Organization classification of central nervous system tumors, the Ki-67 index ranges from <1% to 2% in melanocytomas and is approximately 8% in primary melanomas.[12] In this case, histopathologically, the tumor cells were relatively uniform in size, cells showing mitosis were difficult to find, and the Ki-67 index was 2%; therefore, the tumor in this case was diagnosed as a low-grade melanocytoma. The gene discussed is MKI67; the disease is neoplasm.