• Diagnosis is based on the finding of one or more mucocutaneous ulcers involving the genitalia, perineum, or anus.
• Careful inspection of all genital mucosa is important, as lesions may be inside the foreskin, labia, vagina, or rectum, and may be painless.
• Genital herpes is the most common cause, followed by syphilis.
• A specific pathogen often cannot be identified based on clinical findings alone; laboratory testing should include culture or polymerase chain reaction (PCR) amplification for herpes simplex virus (HSV), and serologic testing for syphilis.
• Despite appropriate testing, no pathogen is identified in up to 50% of patients.