Examination of 93 cases of perianal warts and suggestion of a new classification

PURPOSE: The anatomical distribution of perianal warts is associated with patient characteristics such as sexual orientation. The purpose of this study is to confirm this experiential knowledge using a quantitative classification system and analysis and to obtain findings useful for future treatment. METHODS: From January 2014 to December 2020, 93 patients with perianal warts presented to our hospital. Patients were analyzed for age, sex, lesion site, and recurrence type, among other factors. The lesion site was divided into skin (S) and anal epithelium (anoderm, A), and the number and degree of each were classified into grades 0 to 3. The higher grade between S and A determines its dominant type, such as type S (e.g., S3A1) and type A (e.g., S0A2). RESULTS: The average age of the patients was 39.6 years, and the percentage of patients who were not married was 54.8%. In all, 95.8% of patients were positive for low-risk human papillomavirus (HPV). Type S accounted for 80.6%, whereas type A accounted for 9.7%. Type A cases were all male and were all presumed to be men who have sex with men (MSM). This indicates that the determination of type A may be highly specific for MSM. The type at the time of recurrence was the same type at the time of the first surgery in almost all cases. CONCLUSION: In cases of perianal warts, it is useful to analyze the lesion by considering the range and grade separately for daily clinical practice on proctologist.