Background: Anal cytology (AC) is accepted as a practical screening modality for anal cancer. However, studies suggest that AC and anal biopsy dysplasia correlation is less robust than in cervicovaginal specimens. The current study goals were to look at our institutional experience in a subset of ACs and correlate with surgical pathology (SP), as well as evaluate their Human Papillomavirus (HPV) status.
Methods: 377 ACs from 169 patients (151 males and 18 females) from 2008 to 2017 were included. HPV genotyping (n = 47) and SP within one year of AC (n = 58) were reviewed.
Results: AC/SP was discrepant in 22 cases (37.9%), with a tendency towards AC underestimating the degree of dysplasia. Specifically, any abnormality on AC was 93.8% sensitive for detecting high-grade dysplasia (HGD). However, when requiring a high-grade AC diagnosis, the sensitivity decreases to 12.5%. "Other high-risk HPV" was the most common genotype (57.4%). When considered with all AC with a high-grade diagnosis, co-testing with HPV improved the sensitivity for HGD to 56.3%. Sensitivity improved further to 87.5% when only considering cases with both AC and HPV testing, and were high-risk HPV positive. Furthermore, following review and consensus diagnosis, 8 cases changed from "Discrepant" to "Agreed", reducing the discrepancy rate to 24.1%. Remaining discrepancies were explained by sampling error.
Conclusion: Given the enhanced sensitivity of AC and HPV testing together, and sampling error seen with AC leading to underestimating dysplasia, we recommend AC and HPV co-testing, as well as describing confounding factors in AC reports and obtaining consensus opinion in equivocal cases.
Keywords: Anal canal; Anus neoplasms; Carcinoma-squamous cell; Genotype; Papillomavirus infections; Pathology-surgical; Squamous intraepithelial lesions.
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