Aphthous ulcers are the most common mouth lesion seen in Crohn's. Crohn's can cause granulomatous inflammation in the mouth but it is far less common than the aphthous ulcer. Aphthous ulcers are commonly called "canker sores."
Here is a link to a photo of a single, small aphthous ulcer: Aphthous ulcer picture Please know that an aphthous ulcer can be larger or a person can have many of them together. I once had a bad outbreak of them on the side of my tongue. There were so many they all seemed to run together.
Diagnosed w/ Crohn’s Disease March 2007 On Azathioprine (generic Imuran), Pentasa, & ENTOCORT
Diagnosed w/ Fibromyalgia May 2007 also on Soma
Also have Arthritis, waiting on a EMG nerve test right now...