Anal dysplasia is a pre-cancerous condition which occurs when the lining of the anal canal undergoes abnormal changes. It can be classified as low-grade squamous intraepithelial lesions (LSIL) and high-grade squamous intraepithelial lesions (HSIL) Most cases are not associated with symptoms, but people may notice lumps in and around the anus.broken link
Causes
Anal dysplasia is most commonly linked to human papillomavirus (HPV), a usually sexually-transmitted infection. HPV is the most common sexually transmitted infection.
References
Anal dysplasia Wikipedia(Text) CC BY-SA