A sore looking stomach ...

This 60 year old patient is undergoing a gastroscopy because of early satiety and weight loss. A CLO test was negative
WHAT IS THE LIKELY DIAGNOSIS?

■ Amyloidosis

Could indeed look like this BUT you'd expect the patient to be on haemodialysis!

■ Autoimmune gastritis

Indistinguishable from Hp gastritis but doesn't explain the symptoms

■ CMV gastritis

Possible but more common in children

■ Gastric lymphoma

Could be but you would normally expect ulceration

■ Diffuse type gastric cancer

Yes! The mucosa appears 'swollen' as it's infiltrated by malignant cells spreading between and below the crypts

explanation

As you know, the so called "Lauren’s classification" divides into two types of gastric cancer; the more common 'intestinal type' and the less common 'diffuse type'. 

Actually the molecular workup done by “The Cancer Genome Atlas” Research Network" has actually identified four subtypes: 

1. Epstein-Barr virus positive tumours
2. Microsatellite unstable tumours
3. Genomically stable tumours (diffuse type cancers are in this group)
4. Tumours with chromosomal (the intestinal-type cancer are in this group as the cells have abnormal chromosomal copy numbers; "aneuploidy").

Intestinal type gastric cancer is becoming less common, probably because of the reduced prevalence of H. pylori, whilst the incidence of diffuse type cancers is not falling.  

There are other recognised differences between diffuse and intestinal type gastric cancer. The 'diffuse type' affect younger patients, the sex ratio is identical whilst the 'intestinal type' is more common in men. Presumably this means that known mutagens such as smoking and alcohol does not predispose to diffuse type gastric cancer?  'Diffuse type' cancers are more common in the proximal stomach and can be inherited as part of B-cadherin mutations. Finally, 'diffuse type' cancer develop BELOW the surface epithelium making them very difficult to spot.  There is no irregularity of the overlying crypt or vessel pattern in these lesions.  However, late detection is probably not the only reason why diffuse type cancer have a worse prognosis.