Pedunculated colonic polyps form the "Mexican hat sign." These polyps possess discrete stalks and occasionally can be observed "en face" hanging from the nondependent wall of the colon on double contrast barium enemas.
Almost all cases of colorectal cancer -- also commonly referred to as colon cancer -- begin with the development of benign colonic polyps. These polyps, for reasons still unknown, often turn into cancer, yet they rarely produce noticeable symptoms.
A staging CT scan of chest, abdomen and pelvis was arranged as part of pre-operative staging protocol and this demonstrated a large 3.3 x 4.3 x 3.4cm heterogeneous enhancing colonic polyp, which predominately enhanced with fatty attenuation (Figure 2).