This is classically (40% of the time) a single, firm, painless, non-itchy skin ulceration with a clean base and sharp borders between 0.3 and 3.0 cm in size.
To je deloma pripisati nevarnim seksualnim praksam med moškimi, ki imajo spolne odnose z moškim, porastom promiskuitete in prostitucije ter manj pogostno rabo kondomov.