Case of the Issue

CLINICAL HISTORY

A 55-year-old female patient presented with vague abdominal pain and change of stool habits. Two consecutive fiber optic colonoscopies were incomplete due to colon obstruction at 30 cm. The patient was referred for CT colonography.

The day before the imaging procedure, the patient had a low-residue diet. A total of 60 mL barium 40% w/v was administered in three doses of 20 mL, one each at breakfast, lunch, and dinner (Tagitol V, EZEM). She was also given 18 g of magnesium citrate (Losoprep, EZEM) and bisacodyl tablets (four tablets containing 5 mg). Prior to imaging, carbon dioxide was used to distend the colon. Images were obtained in the supine and prone positions.

FINDINGS

Axial reformatted image (Figure 1) shows the cause of the incomplete colonoscopy to be a 13-cm stenosing segment in the sigmoid colon with incomplete distention and wall thickening. Diverticulae are also seen within the segment (arrows). Axial image in supine position shows a large stalked polyp (Figure 2A, arrows). The same polyp is seen in the prone image, though the head (1 cm) has moved to the opposite side (Figure 2B, arrows).

Endoluminal 3D image shows a 4-mm sessile polyp in the transverse colon near the splenic flexure (Figure 3, arrow). Coronal reformatted (Figure 4A) and endoluminal 3D (Figure 4B) images show thickened haustral folds in the transverse colon, near the hepatic flexure, representing a short stenosing tumor. This is best appreciated on the coronal view. Endoluminal 3D view also shows a thickened haustral fold distal to the ileocecal (IC) valve (Figure 5, arrows).

DIAGNOSIS

The patient underwent anterior resection and right hemicolectomy. Pathological analysis revealed chronic diverticulitis without malignancy in the sigmoid colon (Figure 1), low-grade tubular adenoma with low-grade dysplasia in a large pedunculated polyp (Figure 2), invasive adenocarcinoma (Figure 4), and a flat adenoma with low-grade dysplasia (Figure 5).

A short surveillance schedule (less than three years) was planned to monitor the small sessile lesion (Figure 3)

DISCUSSION

Incomplete colonoscopy due to redundancy or colonic obstruction is well established as an indication for CT colonography.^1-3 Adequate preparation is important if small sessile lesions and flat adenomas proximal to the stenosing lesion are to be detected.⁴ Large pedunculated polyps with long stalks can mimic stool by changing position on supine and prone images. Stool tagging allows these polyps (which remain untagged) to be identified correctly.⁵

Diverticular disease is an important cause of incomplete optical colonoscopy. Differentiating diverticulitis from established fibrosis and tumoral pathology can be difficult. The following are indicative of a benign condition rather than malignancy: The affected segment length is greater than 10 cm, there is no shoulder formation (overhanging edges), and diverticulae are detected in the affected segment.⁶

Care should be taken to differentiate short stenosing tumors from complex haustral folding. Reformatted 2D and endoluminal 3D images should together provide enough information to make the correct diagnosis.⁵

Case submitted by Stefaan Gryspeerdt, M.D., Philippe Lefere, M.D., both radiologists at the Virtual Colonoscopy Teaching Centre in Hooglede, Belgium, and Pierre Cremers, M.D., radiologist at the Máxima Medische Centrum (MMC) in Eindhoven, the Netherlands.