A 43-year-old man presented to our hospital with the chief complaint of melena. An ulcerating lesion suggestive of inflammatory bowel disease was detected in the rectum by colonoscopy. Subsequently, epigastric pain occurred and upper gastrointestinal endoscopy was performed, revealing multiple irregular ulcers throughout the stomach. Immunohistochemical examination of a gastric mucosa biopsy specimen detected Treponema pallidum. In addition, a serological test for syphilis antibody was positive and Treponema pallidum was also found in the rectal lesion. Therefore, the patient was diagnosed as having secondary syphilis with syphilitic gastric and rectal lesions. In this patient, the endoscopic features of the gastric lesions were relatively typical of syphilis. However, the rectal lesion resembled an ulcer caused by inflammatory bowel disease and differential diagnosis was difficult. There have been reports that the number of patients with syphilis has been increasing recently. It will be important for physicians to learn to recognize the endoscopic appearance of gastrointestinal tract lesions caused by syphilis.
