Primary chancre. About 3 weeks after sexual contact, a primary chancre, a painless ulcerated button-like papule, develops at the site of inoculation. This is usually genital (Fig. 1), but oral and anal chancres are seen in men who have sex with men. Regional lymphadenopathy is common. Without treatment, the chancre clears spontaneously in 3–10 weeks. Serology is not positive until 4 weeks after infection, but spirochaetes can be isolated from the chancre.

Secondary stage. This phase starts 4–10 weeks after the onset of the chancre. It is characterized by a non-itchy pink or copper-coloured papular eruption on the trunk, limbs, palms and soles (p. 42). Untreated, the eruption resolves in 1–3 months. Serology is positive.

Tertiary stage. About 30% of patients with untreated syphilis will develop late lesions, usually after a latent period of years. Painless nodules, sometimes with scaling, develop in annular or arcuate patterns on the face or back. Subcutaneous granulomatous gumma – usually on the face, neck or calf – ulcerate, scar and never heal completely (Fig. 2). Cardiovascular syphilis and neurosyphilis may coexist.