Kissing chancre of primary syphilis

A 30-year-old heterosexual man presented with a painless erosion lesion on the coronal sulcus for 3 weeks. It was oval, indurated, slightly elevated kissing erosion with clean, smooth bases (Fig. 1). The lesion in the prepuce, being too hard to bend, would flip over all at once when the prepuce was drawn back (dory flop phenomenon). He was otherwise asymptomatic, and the inguinal lymph nodes on both sides were not enlarged. The patient’s history revealed unprotected sexual intercourse with a female partner 5 weeks before the onset of the lesion. Direct immunofluorescence from the lesion confirmed the presence of treponema pallidum (Fig. 2). A rapid plasma reagin (RPR) test was positive, with a titer of 1:4. In addition, a T. pallidum particle agglutination assay was reactive, and a fluorescent treponemal antibody absorption test was reactive for both IgG and IgM antibodies. Serologic analysis for human immunodeficiency virus was negative. Primary syphilis was diagnosed and the patient received benzathine penicillin G and the lesion resolved within 5 weeks (Fig. 3).