Anal intraepithelial neoplasia in a sexually transmitted diseases outpatient clinic: correlation with cytological screening.

ABSTRACT

BACKGROUND: High-grade anal intraepithelial neoplasia (AIN) is currently considered a precursor of anal cancer. The population most susceptible to AIN is men who have sex with men (MSM), especially if they are infected by HIV. OBJECTIVES: We analysed the population diagnosed with AIN and evaluated anal cytology as a method of screening the at-risk population. METHODS: We undertook a retrospective review of patients diagnosed with AIN by means of a surgical biopsy between 2008 and 2010. We analysed the risk factors of the population affected and the degree of agreement with the cytology performed previously. RESULTS: During the study period 41 patients were diagnosed with AIN and seven with anal canal carcinoma in situ; 77% were men, most MSM. A history of receptive anal intercourse was found in 81% of the patients and in 71% there was an association with anogenital warts; 32 patients were HIV-positive, most of them men. Of the patients with anal dysplasia of any type in the cytology, 90% had some grade of AIN or carcinoma in situ in the later biopsy. The degree of agreement between the cytology and the biopsy was 94% in the high-grade dysplasias and 50% in the low-grade dysplasias. CONCLUSIONS: Anal cytology in at-risk populations has a high degree of agreement with the biopsy when performed surgically, though less in low-grade dysplasias, which must always be studied. More studies evaluating the degree of progression of AIN to anal cancer are necessary.