High-grade squamous intraepithelial lesion with acetowhitening

High-resolution anoscopy images showing high-grade squamous intraepithelial lesions. The arrows in image A show a slightly raised, flat lesion with acetowhitening and coarse punctation after application of 5% acetic acid. Image B is notable for an acetowhite, thickened lesion with notable vascular changes including coarse punctation, mosaic pattern and atypical vessels. These features are consistent with HSIL but can also be seen with early invasion. Biopsies are warranted in such cases to exclude malignancy.