Painful ulcers on the penis

A man in his 50s presented with an eight day history of painful ulcers on his penis. Blisters had appeared on his penis the day after he experienced burning and itching on his prepuce, and within three days these had evolved into painful ulcers. The patient had no fever, headache, malaise, myalgia, oral ulcers, joint pain, or urethral discharge. He had an unremarkable history, no previous diagnoses of sexually transmitted infections (including oral and genital herpes), and he reported no history of unprotected sex. On physical examination, multiple superficial ulcers had formed on an erythematous base on the penis (fig 1). No inguinal lymphadenopathy was present.

Table 1 shows the results of relevant laboratory tests.