Background: Syphilis is a sexually transmitted disease, caused by the spirochete Treponema Pallidum. Many different manifestations exist, which can complicate diagnosis.
Case: A 36-year-old man with a known HIV infection, presented himself with rectal blood loss and abdominal pain. Abdominal ultrasound and abdominal CT were suspicious for malign liver metastases. During subsequent colonoscopy, benign looking rectal lesions were found, possibly caused by either lymphogranuloma venereum or syphilis. Additional diagnostics confirmed an active syphilis infection. After treatment with benzylpenicillin, patient's complaints resolved, as well as the lesions in rectum and liver.
Conclusion: We describe a rare case of a patient with secondary syphilis, presenting with rectal lesions and liver lesions suspicious for malign metastases.