Recto-anal high-grade squamous intraepithelial lesion with 5-year stability: curative endoscopic submucosal dissection.

High-grade squamous intraepithelial lesion (HSIL) is a recognized precursor of anal squamous cell carcinoma (SCC). Randomized controlled trials in human immunodeficiency virus (HIV)-positive individuals have shown that local treatment of HSIL reduces the risk of progression to SCC, but the natural history of HSIL in HIV-negative patients is not well defined. We describe a rare case of recto-anal HSIL in an HIV-negative patient that remained morphologically stable for 5 years. Endoscopically, the lesion measured 33 × 25 mm and extended from the lower rectum (Rb) to the anal canal. The lesion was removed en bloc by endoscopic submucosal dissection (ESD), achieving R0 resection. The pinned en bloc specimen measured 55 × 33 mm, and on histology the lesion measured 44 × 15 mm. Histopathology confirmed HSIL (squamous cell carcinoma in situ) with diffuse p16 positivity, consistent with human papillomavirus infection. Published HIV-negative case-level reports that explicitly document long-term stability without intervention are scarce; this case adds to that under-reported subgroup and supports ESD as a curative, organ-preserving option in selected early-stage cases when en bloc EMR is unlikely.