An ulcer is a crater-like sore on the skin or mucous membrane .
Ulcers form when the top layers of skin or tissue have been
removed. They can occur in the mouth, stomach, and other parts
of the body. Ulcers can be caused by inflammation or infection.
Some ulcers may be caused by a cancer. Habif TM. Principles of
diagnosis and anatomy. In: Habif TP, ed. Clinical Dermatology.
5th ed. Philadelphia, Pa: Mosby Elsevier; 2009:chap 1. Kevin
Berman, MD, PhD, Atlanta Center for Dermatologic Disease,
Atlanta, GA. Review provided by VeriMed Healthcare Network. Also
reviewed by A.D.A.M. Health Solutions, Ebix, Inc., Editorial
Team: David Zieve, MD, MHA, David R. Eltz, Stephanie Slon, and
Nissi Wang.