Mouth ulcers...the causes are too numerous to cover here
adequately..can do one lecture. The most common are apthous ulcers,
which are the common round ulcers with a surrounding white or
reddish rim. The cause is idiopathic in most instances...meaning we
don't know why. People have suggested viruses, but not proven in
most cases. Viruses such as HSV (the commone herpoes simplex) and
varicella-zoster (chicken pox) can certainly cause mouth ulcers but
not the common apthous ulcers that we have. It is most likely
autoimmune but the the honest answer is that we dunno why.
The 'white circular thing' or can also be reddish ring around the
ulcer is a zone of inflammatory cells (white) and vasodilation
(red), often associated with some swelling. That's why it is
painful...cos' it is an inflammatory lesion. As we teach our
medical students, the classic signs of inflammation are rubor
(redness), calor (heat), dalor (pain), tumor (swelling)..
There is some disturbance in the immune system, possibly related to
a viral infection or unknown insults, resulting in inflammation and
breakdown of the surface mucosa.
