What is a sessile polyp, and are they as dangerous as other kinds of polyps?

Maybe: Sessile polyps are flat and broadbased versus a pedunculated polyp that has a narrow stalk. Both have the potential to harbor a malignancy or be pre malignant.

Possibly: They can more easily be missed and are harder to remove though the most important thing is the findings of the polyp type which is determined by the pathologist by looking at the biopsy under the microscope.