Context: - Adenocarcinoma in situ (AIS) is difficult to correctly interpret on Papanicolaou (Pap) cytology slides and false-negative interpretations of AIS can cause significant problems in daily practice.
Objective: - To investigate the false-negative interpretation rate of AIS and the factors related to false-negative interpretation through responses in an educational environment.
Design: - We retrospectively evaluated 11 337 responses in the PAP Education Program (PAP-Edu) from 173 AIS slides from 2011 to 2015. The false-negative interpretation rate, most common false-negative interpretations, and related other factors were evaluated.
Results: - The overall false-negative rate was 6.9% (784 of 11 337). Respondents correctly interpreted AIS 50.0% (5667 of 11 337) of the time; high-grade intraepithelial lesion (HSIL) and malignancies (adenocarcinoma, squamous cell carcinoma, and other carcinomas) accounted for 42.7% (4842 of 11 337) and low-grade intraepithelial lesion accounted for 0.4% (44 of 11 337) of responses. Overall, 92.7% (10 509 of 11 337) of responses were HSIL and above. Among 784 false-negative responses, negative for intraepithelial lesion or malignancy was the most common (61.5% [482 of 784]), followed by reparative changes (24.1% [189 of 784]) and atrophic vaginitis (7.7% [60 of 784]). Overall, pathologists' responses showed a significantly higher false-negative rate than cytotechnologists' responses (8.3%, 403 of 4835 versus 5.7%, 275 of 4816; P < .001). The false-negative response rates were not statistically different among preparation types.
Conclusions: - The low correct interpretation rate and higher false-negative rate for AIS demonstrate the difficulty in interpreting AIS on Pap cytology, which may cause clinical consequences. The higher false-negative rate with pathologists than with cytotechnologists suggests cytotechnologists' higher screening sensitivity for AIS or cautious interpretation to avoid false-positive results by pathologists.