What are the common symptoms of primary syphilis?

Primary syphilis is primarily characterized by chancres and sclerotic lymphadenitis. It may present as a small erythematous patch on the external genitalia; as the disease progresses, the erythema rapidly enlarges and coalesces into larger plaques, becoming indurated. Subsequently, an ulcer develops on the surface of the indurated lesion, and secondary infection may cause pain. Sclerotic lymphadenitis may also occur, manifesting predominantly as painless inguinal lymphadenopathy.