CASE 786 Published on 02.01.2001

Colonic adenomatous polyps and diverticular disease

Section

Abdominal imaging

Case Type

Clinical Cases

Authors

WK Lee, VA Duddalwar, CJ Roche

Patient

57 years, male

Categories
No Area of Interest ; Imaging Technique Digital radiography
Clinical History
57 year old man with lower abdominal pains was investigated with colonoscopy and subsequently referred for a barium enema.
Imaging Findings
57 year old man with lower abdominal pains was investigated with colonoscopy and subsequently referred for a barium enema.
Discussion
A polyp is an abnormal mass which projects into the lumen of a hollow viscus above the level of the mucosa. 10% of polyps are neoplastic and 90% are non-neoplastic (hamartomatous, inflammatory). Neoplastic polyps are epithelial (adenomatous) or non-epithelial in origin. Adenomatous polyps are classified as tubular (75%), tubulovillous (15%) and villous (10%). The distribution is similar to colonic carcinoma ie. rectosigmoid (50%), descending (15%), ascending (15%), and transverse (10%). Adenomatous polyps are pre-malignant and the risk of malignancy is higher if the polyp is villous (30-70%), greater than 2 cm in size (45%), and demonstrates atypia on histology. Incidence of synchronous polyp is 50% and metachronous polyp 30%. Incidence of synchronous colonic carcinoma 1-5% and metachronous carcinoma 5-10%. Radiological signs of a polyp on double contrast enema depends on the angle at which it is viewed and its relationship to the barium pool. Signs include (1) meniscus sign. A meniscus of barium forms around the base of the polyp. When viewed en face, there is a ring shadow with a sharp inner ring due to the soft tissue-barium interface and a fuzzy outer ring due to fading of the barium peripherally. (2) When it lies within a pool of barium, it appears as a negative filling defect. (3) When viewed obliquely, there is a thin meniscus of barium over its surface creating “the bowler hat sign". (4) If the polyp is pedunculated, a stalk is visible with a parallel tram track of barium. These signs are useful to help differentiate a colonic filling defect from a colonic diverticulum. Radiological signs of a diverticulum includes (1) when viewed en face or obliquely, barium pool within the diverticulum creates a sharp outer margin and a fuzzy inner ring as the barium fades centrally. (2) When viewed en face within a pool of barium, the diverticulum fills with contrast and can no longer be differentiated. (3) When viewed tangentially or in profile, the diverticulum protrudes beyond the expected contour of the colon.
Differential Diagnosis List
Colonic adenomatous polyps and diverticular disease.
Final Diagnosis
Colonic adenomatous polyps and diverticular disease.
Case information
URL: https://eurorad.org/case/786
DOI: 10.1594/EURORAD/CASE.786
ISSN: 1563-4086