Treponema pallidum, a spirochete, causes syphilis and is spread through contact with infectious lesions or body fluids. An ulcerative skin lesion, known as chancre, typically develops at the site ...

These lesions usually start as a diffuse area of erythema overlying the point of pressure. Within a relatively short period of time, the skin breaks down and ulcerates. At times the ulcers are ...

Thickened, ulcerated spots called actinic keratoses are precancerous skin lesions that can become a more invasive form of skin cancer when untreated. If you think you have actinic keratoses on ...