MKI67 and gastrointestinal stromal tumor: About 95% of GIST are positive for KIT (CD117), 60-70% for CD34, 30-40% for smooth muscle actin, 5% for S-100 protein, 1-2% for desmin and 1-2% for keratin.[7] In general, tumor size and mitotic index are accepted as two independent prognostic factors for diagnosis.[8] For GIST, prognostic markers that include size larger than 5 cm, mitotic rate >5/50, high-power fields, tumor necrosis and a Ki-67 (MIB-1) index ≥10% all are associated with malignancy and high mortality.[9, 10] Surgery is the mainstay of therapy for GIST when the primary lesion is deemed resectable.