Electrocautery ablation of anal HSIL: correlation of treatment outcomes with histological features and HPV genotypes

Background Electrocautery ablation (EA) is a widely used treatment modality for HPV-induced anal high-grade squamous intraepithelial lesions (HSIL). Roughly half of the targeted HSILs persist or recur following ablation. Several clinical characteristics have been linked to EA resistance; however, there is little data on whether and how ablation outcomes are affected by lesional histology and HPV genotypes. Methods Among lesions that responded to EA and those that recurred, we compared mitotic activity, type of dysplasia (classic vs. keratinized) and degree of dysplasia (AIN2 vs. AIN3). HPV genotypes were tested using cytology samples. Results 97 HIV-infected patients with HSIL underwent EA and surveillance. Upon follow-up (median 10 months, range 5–37), 44 (45%) patients revealed benign or LSIL at the prior ablation site (EA-sensitive group), whereas 53 (55%) revealed HSIL (EA-resistant group). Age, gender, and race distribution were similar regardless of ablation outcomes. The EA-sensitive group tended to have solitary lesions (60%), non-16/18 h-HPV infection (68%), and HPV clearance (18%), whereas the EA-resistant group had multiple synchronous lesions (81%) and HPV16/18 infection (57%). Compared to EA-sensitive lesions, resistant ones were characterized by higher mitotic activity (mean 7 vs. 3/HPF), a higher percentage of AIN3 (70% vs. 36%), as well as the keratinized dysplasia (74% vs. 48%). Conclusions Anal HSIL ablation resistance is associated with multiple synchronous lesions, HPV16/18 infection, high mitotic activity, AIN3, and keratinized dysplasia. Patients with these types of lesions are at high risk of recurrence and warrant careful surveillance.