One month history of rectal bleeding mixed with his stools. He denied any other alarm symptoms. His past surgical history was unremarkable and he took lithium on a regular basis for bipolar disorder. There was no strong family history of bowel cancer. This gentleman was an ex-smoker. Colonoscopy showed a rectal lesion which was biopsied. This showed a tubulovillous adenoma with high grade dysplasia and invasion (early T3 lesion).
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The CT scans corroborated the histology findings and confirmed the presence of a rectal lesion (staged as early T3). However, the CT also showed a lesion in the caecal pole which was described as a 3.7 cm filling defect (see Image 1). A colonoscopy was performed which showed no such lesion. Some months down the line a second re staging CT scan was performed following a long course of radiotherapy. While the rectal lesion showed an excellent response and was virtually undetectable, the lesion in the caecal pole remained unchanged in both size and position (see Image 2). A second colonoscopy was performed which once again could not detect this lesion. Despite two colonoscopies refuting the existence of this lesion, there was conviction among the Radiologists that a caecal lesion was indeed present. To further verify, a CT colonography (virtual colonoscopy) was performed (see Image 3). This once again showed a 2.5-3 cm intraluminal lesion in the pole of the caecum opposite the ileo-caecal valve. However, interestingly, the intraluminal view did not show a separate lesion but only an elongated fold. This led us to believe that this was actually a 'pseudolesion' which was being caused by partial invagination of the loop of distal ileum at the pole of caecum. This was confirmed when the patient underwent an abdominoperineal (AP) resection of their rectal tumour.
CT colonography is a powerful tool which is used for both screening of bowel cancer as well as imaging in symptomatic patients. The companion UK Special Interest Group in Gastrointestinal and Abdominal Radiology (SIGGAR) trials have shown CT colonography as being more superior as compared to barium enema and colonoscopy in patients with symptoms suggestive of colon cancer. Recently, SIGGAR investigators, in Lancet1,2, have reported the findings of two trials which indicate that CT colonography is more sensitive than barium enema and provides a less invasive alternative.
Our case is a very good example highlighting the sensitivity that CT colonography can afford in terms of further characterising suspicious lesions. This in turns allows us to confidently choose the best clinical or surgical approach for the patient. In our case after the CT colonography we were confident of the fact that we were dealing with a single site of disease in the rectum. This allowed us to recommend the surgeons to carry out an AP resection.
Contribution in writing and proof reading this case was also made by Dr Milan Sapundzieski, Consultant Radiologists, Pennine Acute Hospital.
- 1. Halligan S, Wooldrage K, Dadswell E, et al: Computed tomographic colonography versus barium enema for diagnosis of colorectal cancer or large polyps in symptomatic patients (SIGGAR): A multicentre randomized trial. Lancet. February 13, 2013.
- 2. Atkin W, Dadswell E, Wooldrage K, et al: Computed tomographic colonography versus colonoscopy for investigation of patients with symptoms suggestive of colorectal cancer (SIGGAR): A multicentre randomized trial. Lancet February 13, 2013 (early release online).