SYP and cancer: Immunohistochemical staining did not differ between benign and malignant tumors, with positive results for SMA, vimentin, synaptophysin, H-caldesmon, collagen type IV, calponin and negative results for CK-pan, CgA, desmin, CD117, Dog-1, and S-100.[17] The Ki-67 index is around 20% to 30%.