1. Endoscopy Unit, The Second University Clinic, I.M. Sechenov First Moscow State Medical University (Sechenov University), Moscow, Russia
2. Department of Pathology, I.M. Sechenov First Moscow State Medical University (Sechenov University), Moscow, Russia
3. Clinic of Coloproctology and Minimally Invasive Surgery, I.M. Sechenov First Moscow State Medical University (Sechenov University), Moscow, Russia