Primary sore or ulcer at the site of entry of a pathogen; specifically, the typical skin lesion of primary infectious syphilis .
In women it is often internal and may go unnoticed. This single red papule (bump), usually occurring about three weeks after infection, and painless regional lymph-node swelling are the major signs of early-stage syphilis. Identification of Treponema pallidum in its fluid makes the diagnosis. The chancre heals in two to six weeks, but syphilis progresses unless treated with penicillin .