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Session: ePoster: Other Neoplasia and Endoscopy 5 (Mon1015)

EP740 - Radiation-Induced Necrotizing Soft Tissue Infection Complicating Treatment of Anal Cancer

Monday, May 12, 2025
10:47 AM - 10:52 AM PT
Location: Monitor 8, Sails Pavilion, Upper Level

    ePoster Presenter(s)

  • Ashley J. Alden, DO, MS (she/her/hers)

    Colorectal Surgery Research Fellow
    University of South Florida
    Tampa, FL, United States

    All of the relevant financial relationships listed below have been mitigated.
    This individual has no financial relationships with ineligible companies.

    View ePoster

    • Senior Author(s)

  • CM

    Carolina Martinez, MD

    Assistant Professor
    University of South Florida
    Tampa, Florida, United States

    Disclosure information not submitted.

All of the relevant financial relationships listed below have been mitigated.
Ashley J. Alden, DO, MS: This individual has no financial relationships with ineligible companies.
Purpose/Background: Anal squamous cell carcinoma (aSCC) is a relatively rare cancer, accounting for only approximately 0.4% of new cancers annually. Management of aSCC was revolutionized with the application of the Nigro protocol; a completely minimally invasive treatment approach utilizing chemoradiation. Although toxicity in some form results in treatment delays 40-60% of cases, necrotizing infections are an exceedingly uncommon adverse event. This complication results in massive destruction and devastating outcomes for patients, and both incidence and management options are sparsely reported in the current literature.

Methods/Interventions: We present a case of a 41-year-old male with HIV on HAART who was diagnosed with aSCC and underwent treatment with induction chemotherapy followed by chemoradiation per the Nigro protocol for management of his T3N1 disease. One week following completion of his treatment course, he presented to the Emergency Department with shortness of breath and watery rectal discharge. He was ill-appearing, with sepsis physiology, and radiographic evidence of a large, gas-filled, necrotic pelvic collection involving the rectum and bladder. He underwent emergent surgical intervention, which identified extensive necrotizing infection of the pelvis including the sidewall, rectum, anal sphincter complex, inferior bladder involving the trigone, and perineal skin in addition to a rectourethral fistula and large bowel obstruction. On index endoscopic evaluation, the entirety of the anal sphincter complex and anorectal region was obliterated by necrotizing infection. He initially underwent urinary and fecal diversion with nephrostomy tubes and colostomy, respectively, followed by a series of operative debridements for infection control. After resuscitation and extensive critical care, he ultimately underwent a pelvic exenteration with nephrostomy tube placement and interval flap-based reconstruction to his 10 x 10 x 4 cm perineal defect.

This case highlights multiple important considerations. First, NSTI is a rare, life-threatening complication of aSCC treatment that necessitates emergent, multidisciplinary surgical intervention. Second, this case demonstrates the possible heightened risk of this complication in the immunocompromised patient population. Last, it illustrates the impact of their depressed immune status on both functional and aesthetic reconstructive options after resolution of their acute illness.

Results/Outcomes: N/A

Conclusion/Discussion: N/A

Figure 1
Intraoperative Flexible Sigmoidoscopy illustrating complete destruction of anal sphincter complex and distal rectum by necrotizing infection.

Figure 2
CT scan of the abdomen and pelvis with IV contrast demonstrating a large, gas-filled fluid collection in the deep pelvis, obliterating the normal borders of the rectum and bladder.