Late secondary syphilis mimicking anal carcinoma: A case illustration

Syphilis can closely mimic malignancy in both clinical presentation and appearance. We describe a case of a 58-year-old man presenting with painful perianal masses raising concern for anal carcinoma. Serologic testing revealed late secondary syphilis with a rapid plasma reagin titer of 1:128. Treatment with doxycycline resulted in complete clinical resolution and appropriate serologic response, obviating planned biopsy. While condyloma lata were considered as part of the differential, the patient's history, lesion morphology, and distribution were atypical, prompting initial concern for malignancy, This case underscores the importance of early serologic testing to avoid unnecessary invasive procedures in atypical presentations of syphilis.