Carcinoma in situ of anal margin or perianal skin is most commonly squamous and related to oncogenic HPV strains, HIV infection or both. It may present as warty pigmented patches (Bowenoid papulosis).
Also indexed as
Bowenoid papulosis of perianal skinCarcinoma in situ of anal margin or perianal skinHigh grade squamous intraepithelial lesion of anal margin or perianal skinPerianal intraepithelial neoplasia, high grade