Painful Anal Ulcers in an HIV-Negative Young Woman: An Atypical Presentation of Syphilis.

Anorectal syphilis is relatively uncommon and diagnostically challenging given the wide differential diagnosis for anal lesions. Risk factors, such as men who have sex with men or HIV-positive status, are especially important to elicit from patients during the clinical history. In this report, we present a rare case of painful anal syphilis diagnosed in an HIV-negative woman by tissue biopsy.