This was found at Gastroscopy in a middle aged man without any family history undergoing gastroscopy because of an iron deficiency anaemia.
WHAT WOULD YOU DO NEXT?
■ Take a full set of biopsies
■ Organise and EMR
■ Request a capsule study
■ Organise a colonoscopy
■ Request a CT abdomen
There lots of "cystic fundic polyps" and there is also at least one duodenal adenoma. Such findings in a 55-year-old man is suggestive of the "attenuated" form of familial adenomatous polyposis (FAP). In the absence of a family history, presumably this is a new mutation. Of course this means that the most likely reason for the iron deficiency anaemia is a colorectal cancer. This patient needs an urgent colonoscopy!
To remind you, the APC gene is located on the long arm of chromosome 5 and encodes a tumour suppressor protein. APC is a huge protein that no doubt acts in many different ways to help control cell division and cell attachment and preserve the chromosome number through cell division. Normally, APC mops up intracellular ß-catenin. The newly formed “APC– ß-catenin complex” is quickly destroyed. The removal of intracellular ß-catenin is a good thing! Because when a mutated APC gene is less capable of mopping up intracellular ß-catenin, cell-to-cell adhesion is reduced and cells are allowed to stay non-differentiated and immature. That's not good!
Of course there is a second possibility. This could also be a new MYH gene mutation. Briefly, the MUTYH gene encodes 'MUTYH glycosylase', which is a DNA repair enzyme. Similarly to attenuated FAP, patients with MUTYH gene mutations develop multiple colonic polyps in adulthood. However, in contrast to attenuated FAP, patients with MUTYH gene mutations have both an markedly increased risk of both colonic and gastric cancer.
Characteristics of 'attenuated FAP' compared with 'classic FAP' are: