A comparative study between conventional and liquid-based cytology in screening for anal intraepithelial lesions in HIV-positive patients.

Anal intraepithelial neoplasia (AIN) is associated with HPV infection and can be detected by cytological screening. While conventional exfoliative cytology (CC) is a low-cost and nonaggressive method, liquid-based cytology (LBC) tends to give clearer readings. Although studies of the efficacy of anal cancer screening methods would be of great importance for groups at high risk for AIN, few such studies have been conducted. The aim of the present study was to assess the concordance of CC and LBC in diagnosing anal pre-neoplastic lesions, and to compare cytological results with anoscopy, histopathological, and molecular biology findings. Comparative study involving 33 HIV-positive patients, who underwent anoscopy and biopsy of suspected lesions. Concordance between the two cytology methods was calculated, as were the associations between cytology results and findings from other screening methods. A total of 54.5% of cases were considered AIN-negative by CC and LBC, and concordance between the two methods was statistically significant (P < 0.05). Anoscopy was negative in 15 of the 18 CC- and LBC-negative cases. CC identified 75% of patients with positive biopsy, while LBC identified 85.71% of these patients. Molecular biology results showed that patients with LSIL tested positive for the highest number of HPV subtypes. The associations between positive biopsy and high grade HPV, HPV 16, and multiple HPV infections were not statistically significant. Conventional and liquid-based cytology are equally effective in screening for anal preneoplastic lesions.