Anal intraepithelial neoplasia and HD anoscopy
Anal intraepithelial neoplasia (AIN) is a precursor lesion of anal squamous cell cancer (aSCC). aSCC is considered a rare cancer, but its incidence is on the rise and in certain high-risk populations it approaches the incidence of colorectal cancer. Although controlled randomized trials are lacking, expert opinions support screening and therapy of this anal neoplasia in the high-risk groups. AIN/aSCC belongs among neoplasia associated with HPV infection. Individuals with a higher AIN/aSCC risk can be examined by rectal smear for cytology or more sensitive HPV DNA, not unlike the cervical cancer screening. In the case of a positive result, high-resolution anoscopy is recommended. However, this is not a common practice. The goal of this study is to acquaint the gastroenterology community with the not so well known AIN diagnosis and offer a new active approach to its detection and therapy. We retrospectively analyzed a cohort of 18 patients indicated for flexible anal endoscopy because of their higher risk of anal neoplasia or to explain rectorrhagia after normal colonoscopic finding. We named the anal examination with the use of flexible high-definition endoscope by the new term, high definition (HD) anoscopy. The detected lesions were removed by endoscopic mucosal resection (EMR) or biopsied and the samples sent for histopathological evaluation by one pathologist. Among 18 examined patients, AIN was diagnosed in 12 and the riskier AIN II/III was found in 7. In most cases the lesions were type IIa or Is according to Paris classifications. In all AIN cases irregularities of the mucosal IPCL vessels (intrapapillary capillary loops) were present. Based on our results we recommend active examination of the often neglected anorectal region by the flexible HD endoscope. High resolution and digital chromoendoscopic technology of modern endoscopes offers an easy way to detect and treat AIN without a risk of anal dysfunction.
Keywordsanální intraepiteliální neoplazie, lidský papilomavirus, skvamózní karcinom anu, anoskopie s vysokým rozlišením
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