P0564 Sexually Transmitted Infections Mimicking Inflammatory Bowel Diseases: Case Series of Infectious Proctitis
Authors: Mattana M , Sbrozzi-Vanni A , Lapenna L , Fonte S , Cusi G , Faggiani R , Merli M 
Published: January 2025

Abstract

Background
Sexually transmitted infections (STIs) are increasingly recognized as causes of proctitis, particularly among men who have sex with men (MSM). These infections frequently mimic inflammatory bowel diseases (IBD) in clinical, endoscopic, and histological presentations, leading to potential misdiagnosis and inappropriate treatments. Accurate recognition requires detailed sexual history and targeted diagnostic tests.

Methods
Patients were identified from IBD outpatient visits (2021–2023) and retrospectively selected for suspected infectious proctitis mimicking IBD. Diagnosis was confirmed via clinical evaluation, targeted tests (rectal swabs, PCR, serology), and histology. Follow-up continued for six months post-treatment.

Results
1. A 42-year-old MSM with secondary syphilis treated with benzathine penicillin presented with bloody diarrhea, tenesmus, anorectal pain, and 10-kg weight loss. Mild anemia (Hb 12 g/dL) and elevated CRP were noted. Rectosigmoidoscopy (RSCS) revealed fibrinous ulcers causing luminal narrowing. Rectal swabs confirmed Chlamydia trachomatis. Treatment with doxycycline led to clinical and endoscopic resolution at six months.
2. A 33-year-old MSM with unprotected intercourse reported mucorrhea and tenesmus for one month. Calprotectin levels were elevated (861 µg/g). Colonoscopy revealed mild proctitis with mucosal hyperemia, and histology showed mild-to-moderate inflammation with crypt abscesses. Swabs confirmed Neisseria gonorrhoeae. Ceftriaxone resolved symptoms and normalized calprotectin (40 µg/g).
3. A 34-year-old male with primary sclerosing cholangitis (PSC) presented with two weeks of tenesmus, anal bleeding, and pruritus. Colonoscopy appeared macroscopically normal, but histology revealed human papillomavirus (HPV) infection. Anal canal condylomas were identified and successfully treated with cryotherapy, resulting in significant relief.

Conclusion
The rising prevalence of STI-related proctitis highlights the need for awareness among clinicians, as these infections often mimic IBD. Misdiagnosis can lead to inappropriate treatments, including steroids or biologics, causing adverse effects and delays in proper management. Detailed sexual history and targeted diagnostics, such as PCR and rectal swabs, are critical for accurate identification and effective treatment. These cases emphasize the critical role of integrating sexual history into clinical evaluation for proctitis. Awareness and timely recognition of STI-related proctitis are crucial to avoid misdiagnosis as IBD, ensure effective and targeted treatment, improve patient outcomes, and prevent inappropriate and prolonged follow-up.

References
-Infectious Proctitis: When to Suspect It Is Not InflammatoryBowel DiseaseFrank Hoentjen • David T. Rubin (Dig Dis Sci (2012) 57:269–273)
-Proctitis: a glance beyond inflammatory bowel diseasesStefano Rizza et all Minerva Gastroenterol Dietol. 2020 Sep;66(3):252-266
-Proctitis in Men Who Have Sex with Men. Julia M. Steed et all