[Rectal Syphilis Mimicking Malignancy: A Case Report].

Rectal syphilis is a rare form of syphilis presentation and its symptoms, endoscopic and radiologic findings are nonspecific. Rectal syphilis typically presents with features such as concentric rectal wall thickening, mucosal hyperemia, perirectal fat stranding, and lymphadenopathy. Rectal cancer exhibits asymmetric wall thickening and lymph node necrosis, aiding in the differentiation between these two diseases. However, due to the considerable overlap in their respective manifestations, distinguishing between rectal syphilis and rectal cancer is extremely challenging without considering the patient's medical history. Rectal syphilis often leads to unnecessary tests or delayed treatment, as it can be mistaken for other benign diseases such as inflammatory bowel diseases in addition to rectal cancer. In this case report, we aim to provide a detailed report on the endoscopic, imaging, and pathological findings based on our experience with a case of suspected rectal malignancy that turned out to be rectal syphilis.