Jordan K. Voss, MD, MS, Ahmed T. Kurdi, MD, Manuel Braga Neto, MD, Xiao Jing Wang, MD, Victor Chedid, MD, MS Mayo Clinic, Rochester, MN
Introduction: The incidence of anal cancer has increased over two-fold since 1975 with an estimated 8,590 new cases and 1,350 deaths in 2020. Anal squamous cell carcinoma (ASCC) arises from the progression of anal intraepithelial neoplasia (AIN), a precursor lesion resulting from infection with high-risk strains of HPV. Additional risk factors for ASCC include HIV infection, men who have sex with men, and anoreceptive intercourse. Despite well-defined risk factors, screening guidelines do not currently exist due to a lack of studies demonstrating a mortality benefit. As such, screening for ASCC is variable. Colonoscopy, whether performed for routine colorectal cancer screening or for the evaluation of gastrointestinal symptoms, provides an opportunity for the early detection of anal cancer and its precursor lesions through rectal retroflexion (RR) views of the anal canal. The aim of this study is to review the endoscopic detection of AIN and ASCC.
Case Description/Methods: A total of five cases of AIN or ASCC were identified. Four cases of AIN were incidentally discovered on RR during colonoscopy in females age 55 to 71. One patient had a history of high-risk cervical HPV while the remaining patients had no prior HPV tests documented. None had been previously screened for AIN or anal HPV. Anal lesions identified on RR views included sessile polyps, nodular mucosa, and circumferential polyps with enhanced visualization on narrow band imaging. On histologic examination, two of the four patients had high-grade squamous intraepithelial neoplasia and the remaining two had low-grade intraepithelial neoplasia. All four of the patients were referred to colorectal surgery for anoscopy and underwent excision/destruction of the lesions. The fifth case was a 70 year-old female who presented with epigastric pain and was found to have inguinal lymphadenopathy and a 2 cm anal mass on examination. Diagnostic colonoscopy revealed a 3 cm ASCC which was confirmed on biopsy. Of note, this patient had undergone surveillance colonoscopy at an outside institution 21 months prior with no lesions noted on RR.
Discussion: AIN and ASCC may have a variable appearance on endoscopic evaluation. Thorough RR views with use of NBI should be obtained and suspicious anal mucosa warrants biopsy and histologic evaluation. Patients with positive findings should be referred for surgical excision and subsequent surveillance.
Figure: High-grade squamous intraepithelial lesion (AIN 2-3) on rectal retroflexion views. The images on the left (A and C) represent two separate cases. The images on the right (C & D) are of the same two lesions viewed with NBI enhancement.
Disclosures: Jordan Voss indicated no relevant financial relationships. Ahmed Kurdi indicated no relevant financial relationships. Manuel Braga Neto indicated no relevant financial relationships. Xiao Jing Wang indicated no relevant financial relationships. Victor Chedid indicated no relevant financial relationships.
Jordan K. Voss, MD, MS, Ahmed T. Kurdi, MD, Manuel Braga Neto, MD, Xiao Jing Wang, MD, Victor Chedid, MD, MS. P1500 - Detection of Anal Intraepithelial Neoplasia and Anal Squamous Cell Carcinoma on Colonoscopy: A Case Series, ACG 2021 Annual Scientific Meeting Abstracts. Las Vegas, Nevada: American College of Gastroenterology.