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The value of anal cytology and human papillomavirus typing in the detection of anal intraepithelial neoplasia: a review of cases from an anoscopy clinic
  1. P A Fox1,
  2. J E Seet2,
  3. J Stebbing3,
  4. N Francis2,
  5. S E Barton1,
  6. S Strauss4,
  7. T G Allen-Mersh5,
  8. B G Gazzard1,
  9. M Bower3
  1. 1Department of HIV and Genitourinary Medicine, Chelsea and Westminster Hospital, 369 Fulham Road, London SW10 9NH, UK
  2. 2Department of Histopathology, Department of Histopathology, Charing Cross Hospital, Hammersmith Hospitals NHS Trust, London W6 8RF, UK
  3. 3Department of Oncology, Chelsea and Westminster Hospital, London, UK
  4. 4HPV Reference Laboratory, Health Protection Agency, 61 Colindale Avenue, London NW9 5HT, UK
  5. 5Department of General Surgery, Chelsea and Westminster Hospital, London, UK
  1. Correspondence to:
 P A Fox
 Department of HIV and Genitourinary Medicine, Chelsea and Westminster Hospital, 369 Fulham Road, London SW10 9NH, UK;


Background: Previous studies have reached differing conclusions about the utility of anal cytology as a screening tool for anal intraepithelial neoplasia (AIN). There is a need also to establish whether HPV typing offers a useful adjunct to screening.

Methods: We analysed data from 99 consecutive homosexual/bisexual male patients (89 HIV-1 positive) who underwent high resolution anoscopy. Follow up visits for these patients were also included, giving a total of 160 anoscopic procedures. Comparison was made between results of anal cytology using the sampling method of Palefsky, and histological findings of biopsies taken from abnormal areas seen on high resolution anoscopic examination of the anal canal. Swabs taken concurrently with the cytology were analysed for the presence of human papillomavirus (HPV) DNA and compared with the cytological and histological findings.

Results: The sensitivity of the cytology was 83%, and the specificity 38% when compared with histology. At screening of 34 asymptomatic men, 83% had anal cytological dysplasia and 78% had AIN. There were no significant differences in the prevalence of hrHPV genotypes between different cytological or histological grades of abnormalities.

Conclusion: Anal cytology by the Palefsky method is simple to undertake, has a sensitivity and specificity comparable with cervical cytology, and can therefore be used as the basis of a pilot screening project in centres with large cohorts of HIV positive homosexual men who have a high risk of developing anal carcinoma. HPV genotyping is not a useful adjunct to cytological screening.

  • AIN, anal intraepithelial neoplasia
  • HAART, highly active antiretroviral therapy
  • HPV, human papillomavirus
  • hrHPV, high risk HPV
  • PBS, phosphate buffered saline
  • PYAR, person years at risk
  • anal intraepithelial neoplasia
  • cytology
  • human papillomavirus

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