A 70-year-old male was referred for a routine CT scan of the abdomen and pelvis with intravenous and oral contrast.
Incidental finding: 4 cm homogeneous nodule high left lateral wall of the rectum.
The patient was referred for colonoscopy and a firm non-bleeding 4 cm mass consistent with adenoma was found 10 cm from the anal margin. The mass was too high to be palpated on rectal exam. Biopsies were obtained. The mass was a villous adenoma, without high-grade dysplasia, it was however too large to be removed endoscopically, and the patient underwent surgical low anterior resection.
It is not uncommon to find large colonic masses on routine scans, especially with thinner cuts obtained with modern multidetector CT scans.
We routinely follow the lumen of the colon from rectum to cecum on every single scan (“lumen tracking”). Solid lesions and large adenomas are homogeneous, enhance following contrast injection and can be differentiated from stool in the colon, which usually mix with barium/oral contrast and contain air bubbles.
Rectal mass, endoscopic images
