1463 Underwater Cap-Assisted Endoscopic Diagnosis and Treatment of Anal Intraepithelial Neoplasia

Abstract

INTRODUCTION: Anal intraepithelial neoplasia (AIN) is a premalignant lesion which can progress to squamous cell carcinoma of the anus. Although rare, therate of anal canal cancer is rising within the United States and is associated with significant morbidity and mortality. Early detection of premalignant lesions is critical. AIN is frequently missed because detailed examination of the anal canal is difficult. Here we present two cases describing techniques to aid in the diagnosis and resection of AIN including endomicroscopy, distal attachment caps, and underwater endoscopy. CASE DESCRIPTION/METHODS: Patient 1 A 78-year-old woman with a history of HPV and AIN presented for follow up. A flexible sigmoidoscopy (FS) with a distal attachment cap was used to examine the anal canal and revealed two verrucous polypoid-appearing lesions just distal to the dentate line. Probe based confocal endomicroscopy of these lesions showed abnormal cellular structure and capillaries. The lesions were completely resected using a combination of biopsy forceps and cold snare. Both lesions were consistent with high-grade squamous AIN II-III. Repeat flexible sigmoidoscopy 6 months later showed no evidence of recurrence. Patient 2 A 63-year-old woman with a history of AIN with high grade dysplasia was referred to our center for resection. FS with a ESD cap attachment and water-immersion revealed a 5 mm villiform lesion (Figure 1). Using water-immersion the lesion appeared to float up off the mucosa. Probe based confocal endomicroscopy showed highly vascularized abnormal cellular architecture. The lesion was removed with cold forceps and pathology was consistent with low grade squamous AIN I. A follow up FS 1 year later showed a lesion consistent with AIN using narrow band imaging and near focus (Figure 2 and 3). The lesion was removed in piecemeal fashion with cold forceps underwater. Pathology again was consistent with low grade squamous AIN 1. DISCUSSION: Here we described techniques to improve identification and resection of AIN. Our approach is to use an ESD cap which helps stabilize the scope tip in the anal canal and spread mucosal folds to flatten areas of interest. Confocal probe based endomicroscopy has been described to take “optical biopsies.” Narrow band imaging and near focus of endoscopic images aids in the identification of lesions. Finally, water-immersion technique frequently causes AIN lesions to float up off the mucosa which aids in identification and resection.