The specimen is a length of large intestine opened to show a sessile polypoid tumour at the upper
end. The tumour has a coarsely nodular surface. There is not likely to be any obstruction with a
lesion such as this, and the tumour does not appear to be ulcerated. A segment of the tumour has
been taken for histology established that this is an invasive carcinoma arising in a tubulovillous
adenoma, although the large size of the lesion and the fact that it is sessile make this likely based
on macroscopic appearances. Beneath the tumour, there is a pendunculated adenomatous polyp.
One would need to examine sections of this to be sure it does not harbour invasion but this seems
unlikely based on macrocopic appearances because the lesion is small and has a stalk. In the centre
of the specimen is a small mucosal nodule (3mm), likely a hyperplastic polyp. Note that
adenomatous polyps show dysplasia histologically and are considered to be pre-cancerous lesions.
Hyperplastic polyps do not show dysplasia and it is generally believed that they do not progress to