alt=See caption. The first sign of<unk>  is a painless swollen<unk> mp on the arm or leg, often similar in appearance to an insect bite. Sometimes the swollen area instead appears as a patch of firm, raised skin about three centimeters across called a "plaque"; or a more widespread swelling under the skin. Over the course of a few weeks, the original swollen area expands to form an irregularly shaped patch of raised skin. After about four weeks, the affected skin sloughs off leaving a painless ulcer.<unk> s typically have "undermined edges", the ulcer being a few centimeters wider underneath the skin than the wound itself. In some people, the ulcer may heal on its own or remain small<unk> t linger unhealed for years. In others, it continues to grow wider and sometimes deeper, with skin at the margin dying and sloughing off. Large ulcers may extend deep into underlying tissue, causing bone infection and exposing muscle, tendon, and bone to the air. When ulcers extend into muscles and tendons, parts of these tissues can be replaced by scar tissue, immobilizing the body part and resulting in permanent disability. Exposed ulcers can be infected by other bacteria, causing the wound to become red, painful, and foul smelling. Symptoms are typically limited to those caused by the wound; the disease rarely affects other parts of the body.<unk> s can appear anywhere on the body,<unk> t are typically on the limbs. Ulcers are most common on the lower limbs (roughly 62% of ulcers globally) and upper limbs (24%),<unk> t can also be found on the trunk (9%), head or neck (3%), or genitals (less than 1%). The World Health Organization classifies<unk>  into three categories depending on the severity of its symptoms. Category I describes a single small ulcer that is less than . Category II describes a larger ulcer, up to , as well as plaques and broader swollen areas that have not yet opened into ulcers. Category III is for an ulcer larger than 15 centimeters, multiple ulcers, or ulcers that have spread to include particularly sensitive sites such as the eyes, bones, joints, or genitals.
Buruli ulcer
Lichen planus
Callous ulcer
Lichen sclerosus
Kangri ulcer
Lipschütz ulcer
Stercoral ulcer
Melanosis coli