It could mean he has a colon ulcer.
under run gastric ulcer means an ulcer in the stomach that is asymptomatic and incidentally detected on routine examination.
As any desease, time is the worst enemy. If the ulcer is inattentive, the condition will turn into cancer. That is the risk.
It means tissue of the colon
The colon compares two numbers in a ratio
I have found blood in my stool does this mean colon cancer
Peptic Ulcer Disease
That is one possibility.
I'm not sure if you mean simply a "duodenal ulcer', which would be the most common wording of the diagnosis.
A friable colon is one that is easily upset or irritated. It can become swollen and could lead to colon disease.
Stolen Colon!
NUD = NON-ULCER DYSPEPSIA