Serrated lesions of colon

A broad spectrum of lesions ranging from benign to malignant found in colon. The lesions comprised of micro vesicular hyperplastic polyp, goblet cell rich hyperplastic polyp, sessile serrated lesion, sessile serrated lesion with dysplasia, traditional serrated adenoma and serrated carcinoma.^[1] Serrated lesion simply means saw tooth morphology on surface of the polyp and crypt.^[2] Serrated lesions are very difficult to diagnose on histology and its very important to diagnose such polyps as sessile serrated polyps can transform to carcinoma. They are more common on right side of colon and carry BRAF mutation.^[3] The progression of sessile serrated polyp to cancer follows serrated pathway. Histologically, marked serrations at the base of the crypt with distorted architecture will be seen.^[4] The traditional serrated adenoma also carries the risk of malignancy and have K-RAS mutation. Histologically, show villous or tubulovillous architecture having columnar cells with diffusely eosinophilic cytoplasm along with aberrant crypts.^[5] The three molecular features of serrated polyps are BRAF mutation, KRAS mutation and CpG island methylation. The sessile serrated polyp progress through BRAF serrated pathway and traditional Serrated polyps by KRAS serrated pathway accounting to 15-20% of colorectal cancer.^[6] The knowledge about serrated lesions aids in the better management of colorectal cancer.