Expansion
Intestinal type from atrophic gastritis, diffuse type with signet ring cells
Expansion
Intestinal type
- Arises from chronic atrophic gastritis and intestinal metaplasia, usually driven by Helicobacter pylori
- Forms a discrete mass or ulcer, commonly in the antrum
- Better prognosis; declining incidence with falling H pylori prevalence
Diffuse type
- Signet ring cells infiltrating the wall, with loss of E-cadherin (CDH1)
- Linitis plastica: diffuse infiltration giving a rigid, thickened, non-distensible stomach
- No precursor lesion, younger patients, worse prognosis, familial form with germline CDH1
Risk factors: H pylori, smoked and salted foods, nitrosamines, smoking, pernicious anaemia, previous partial gastrectomy, blood group A.
Characteristic metastases are worth learning as a set:
- Virchow node: left supraclavicular, giving Troisier sign
- Sister Mary Joseph nodule: periumbilical
- Krukenberg tumour: bilateral ovarian deposits, transcoelomic, with signet ring cells
- Blumer shelf: rectovesical pouch deposits palpable on rectal examination
H pylori also causes gastric MALT lymphoma, which can regress with eradication alone.