<prompt> A 23-year-old presented with painless penile ulcer and painless lymphadenopathy. What is the diagnosisChancroidDonovanosisSyphilisHerpes  <response>: In syphilis, the primary lesion is the chancre at the site of entry of the spirochete. In all but a few, the chancre is genital. Other common sites are the mouth and nipples. The chancre is painless, relatively avascular, circumscribed, indurated, superficially ulcerated lesion. It is known as hard chancre to distinguish it from the non-indurated lesions of soft chancre caused by H.dureyi. Ref: Textbook of microbiology; Ananthanarayan and panikers; 10th edition; Pg:379 