Sessile polyps are very rarely malignant, states American Cancer Society. Out of 87 sessile polyps excised from 51 patients, only three were malignant, notes a report published by the U.S. National Library of Medicine.
Polyps are mostly benign and non-cancerous growths, but cancer develops some types of polyps, notes American Cancer Society. Sessile refers to the shape of the polyp. A sessile polyp has a slightly flattened, broad-based shape; as opposed to serrated polyps that have a saw-tooth appearance, notes American Cancer Society. Pathologists can determine whether or not a polyp is malignant by analyzing biopsy samples under a microscope.