[A Case of Rectal Syphilis Incidentally Found at Regular Medical Check-up].

Syphilis is a rare disease in the rectum. It is difficult to diagnose because the characteristics of the rectal syphilis rectal lesion are highly varied. The endoscopic findings of rectal syphilis are proctitis, ulcers, and masses. If rectal syphilis is suspected to be the cause for rectal lesions, it is important for physicians to consider the sexual history and sexual orientation of the patient. We report a case of incidental rectal syphilis in a 41-year-old man diagnosed during a regular medical check-up.