S5177 Herpes Simplex Virus Proctitis Mimicking IBD in an Immunocompetent Male: A Case Report

Introduction: Herpes simplex virus (HSV) proctitis is an uncommon diagnosis in immunocompetent individuals and can be missed, especially when initial laboratory and serologic tests are negative. This case aims to show the importance of early endoscopic evaluation and tissue sampling in patients with persistent proctitis symptoms, rather than relying solely on empiric therapy or serologic testing. Case Description/Methods: A 29-year-old man with no significant medical history, but with a history of receptive anal intercourse, presented with a month of epigastric pain, nausea, and bloating following unprotected anal exposure. His symptoms soon worsened with rectal prolapse, bloody purulent discharge, and diarrhea. Despite negative sexually transmitted infection screening at a sexual health clinic, his symptoms persisted. Upon hospital admission, laboratory studies revealed a white blood cell count of 19,000. Computed tomography (CT) imaging showed small bowel intussusception, rectal wall thickening, and extensive lymphadenopathy. He was started on empiric antibiotics—ceftriaxone, doxycycline, and metronidazole—but was lost to follow-up before his symptoms resolved. Nearly a year later, he returned with ongoing hematochezia and fever. Subsequent colonoscopy revealed edematous, friable, and ulcerated mucosa in the rectosigmoid region. Biopsies demonstrated marked cryptitis and ulceration with confirmation of both HSV-1 and HSV-2 on the immunohistochemical staining, while stains for cytomegalovirus and Treponema pallidum were negative. Notably, HSV polymerase chain reaction testing was negative. Discussion: This case highlights 2 important lessons for gastroenterologists. First, persistent proctitis symptoms should prompt early colonoscopic evaluation with tissue sampling. Relying solely on empiric treatment or serologic testing can delay diagnosis and prolong morbidity. Second, HSV proctitis can present with systemic features such as small bowel intussusception and extensive lymphadenopathy, closely mimicking inflammatory bowel disease or malignancy. Recognizing that HSV proctitis may be part of a broader inflammatory process is key to ensuring an accurate assessment and timely management.