Context: Anal cytology is being used more frequently for anal cancer screening, yet many cytologists are unfamiliar with it.
Objective: To describe the performance of anal cytology in the College of American Pathologists' Interlaboratory Comparison Program in Non-Gynecologic Cytology (CAP NGC) educational slide program during a 6-year time span, from 2006 to 2011, using participant responses (pathologist, cytotechnologist, and laboratory).
Design: Concordance rates for the target diagnosis and general category for each slide challenge were analyzed. Four main factors were included in the analysis: (1) general category or specific responses, (2) program year from 2006 to 2011, (3) participant type (pathologist, cytotechnologist, or overall laboratory), and (4) preparation type (liquid-based or conventional).
Results: Participants most frequently correctly classified negative for intraepithelial lesion or malignancy, low-grade squamous intraepithelial lesion, and herpes simplex virus infection, with concordance rates of 78.8%, 85%, and 80.2%, respectively. Performance on challenges with target diagnoses of high-grade squamous intraepithelial lesion (HSIL), squamous cell carcinoma, and ameba was poor, with concordance rates of 57.1%, 56.2%, and 41.5%, respectively. Significant improvement during the 6 years was seen in the concordance rates of participants' responses for low-grade squamous intraepithelial lesion challenges but not for HSIL. There was no significant difference in performance by slide preparation type.
Conclusions: The poor performance on anal cytology in the CAP NGC program, especially with regard to correct identification of HSIL and squamous cell carcinoma, indicates that there is a need for continued education about anal cytology.