The results of Ki-67 antigen expression highlighted that 15 mast cell tumors (17.2%) had a Ki-67 index equal to 0 positive nuclei, 22 (25.3%) and 20 (23%) had Ki-67 index of 1 and 2 positive nuclei, respectively, while the remaining had a Ki-67 index ≥3 of positive nuclei, ranging from 3 to 15 (Figure 1A,B, Table 2). Here, MKI67 is linked to mast cell neoplasm.