OMED E-Newsletter Issue 1, 2009: Brainteaser/image of the month
This is the stomach (left) and second part of duodenum (right) in a 55 year old man undergoing gastroscopy to investigate iron deficiency anaemia.
What would you organise next?
- gastric biopsies with immunohistochemistry staining for e-cadherin
- serum gastrin levels
- a colonoscopy
- a capsule endoscopy
- a duodenal EMR
Correct answer: c
This patient has cystic fundic polyps and a duodenal adenoma. This finding in a 55 year old man is suggestive attenuated familial adenomatous polyposis. The most likely reason for his iron deficiency anaemia is a colorectal cancer.
Classically in attenuated FAP, there are fewer colonic polyps (average of 30) , polyps and cancers are more frequent on the rights side of the colon, patients are older at presentation (average about 44 years) the risk of cancer is lower (70% at age of 80) and cancer develops at a later age (average 56 yrs) than in classic FAP.
Patients may be offered APC gene testing and genetic testing for MYH mutations. Attenuated FAP has been associated with mutations towards the 5’ part of the APC gene on the long arm of chromosome 5. The MYH (mutY Homolog (E. coli) gene codes for MUTYH glycosylase, a DNA repair enzyme. Patients with MUTYH gene mutations develop colonic polyps in adulthood.
Mutations in the APC tumour suppressor gene is thought to be one of the early steps in the adenoma-to-carcinoma sequence. The normal APC gene binds intracellularly to beta-catenin preventing it from increasing cell-to-cell adhesion and promoting proliferation. Instead the APC-beta catenin complex becomes targeted for degradation.
The APC protein is a huge protein which no doubt helps to control cell division, cell attachment and preserving the chromosome number through the cell division in many different ways.
Reference: Lynch HT et al. Cancer 1995;76 (12):2427-2433.