Cecal pseudolesion (CT colonography)

An unusual case of a caecal 'pseudolesion'Caecal pseudolesion

This gentleman was referred with a oneOne 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).

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 intra luminalintraluminal 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. thisThis 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.