The reporting of anal cytology and histology samples: establishing terminology and criteria.

Our understanding of the human papillomavirus (HPV) related cytomorphology and histopathology of the anal canal is underpinned by our knowledge of HPV infection in the cervix. In this review, we utilise cervical reporting of cytological and histological specimens as a foundation for the development of standardised and evidence-based terminology and criteria for reporting of anal specimens. We advocate use of the Australian Modified Bethesda System 2004 for reporting anal cytology. We propose the use of a two-tiered histological reporting system for noninvasive disease - low-grade and high-grade anal intraepithelial neoplasia. These classification systems reflect current understanding of the biology of HPV and enhance diagnostic reproducibility. Biomarkers such as p16(INK4A) may prove useful in further improving diagnostic accuracy. Standardisation is important because it will increase the value of the data collected as Australian centres develop programs for screening for anal neoplasia.