Hamish, a 23-year-old retail worker, presents after one week of fever, myalgia and malaise. 

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<p>Hamish, a 23-year-old retail worker, presents after one week of fever, myalgia and malaise.</p><p>He also has a painful rash on the penis and pubis, which has been gradually worsening over the past five days.</p><p>Hamish had unprotected sexual encounters with men during a trip to China two weeks ago. He is usually very well, and his last STI screen three months ago was negative.</p><p>On examination he has a fever of 38.6°C and the rash (pictured) is isolated to the penis and pubic region.</p><p>Each lesion has a central umbilicated necrotic black crust with peripheral oedematous erythema. There is tender left inguinal lymphadenopathy.</p><p>A PCR swab is negative for varicella–zoster virus, HSV and syphilis, and serological tests for syphilis and HIV are negative.</p>

Dr Kate Kelso is a GP and medical editor at Australian Doctor.