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


  • Conflict of interest

    • The authors declare no conflict of interest.
  • Funding sources

    • None.



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.


We analysed the population diagnosed with AIN and evaluated anal cytology as a method of screening the at-risk population.


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.


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.


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.