MIB1 and neoplasm: A practical grading system for GIST after surgical resection was proposed by Bucher et al. [22] including 5 minor (tumor size ≥5 cm, mitotic index ≥5 mitoses/50 hpf, presence of necrosis, infiltration of adjacent structures, and MiB1 index > 10%) and two major (presence of LN invasion and/or metastasis) criteria.