Utility of ProExC and IMP3 immunocytochemical staining in atypical glandular cells of undetermined significance in liquid-based cervical cytology.

The diagnosis of atypical glandular cells of undetermined significance (AGUS) in liquid-based cervical cytology specimens shows significant underlying pathology in only 30% of cases, while the remaining cases are found to be benign (reactive, reparative/metaplastic). Previous studies have reported positive ProExC and IMP3 staining in neoplastic glandular lesions of the uterine cervix and corpus. We present our experience with the utility of these markers in the evaluation of AGUS cases in liquid-based cervical cytology. The case cohort included 34 cases diagnosed as AGUS. ProExC and IMP3 immunocytochemical (ICC) stains were performed on ThinPrep® slides and the results correlated with subsequent biopsy findings. Positive expression was classified as strong diffuse nuclear immunostaining for ProExC and granular cytoplasmic for IMP3. The presence of AGUS cells on the ICC stained slides was confirmed in all cases. IMP3 was positive in 80% of glandular neoplasms and negative in 93% non-glandular lesions/cases negative for squamous intraepithelial lesion (SIL). ProExC was positive in 60% of glandular neoplasms and negative in 83% non-glandular lesions/cases negative for SIL. When used as a panel (ProExC + IMP3), at least one stain was positive in 100% of glandular neoplasm cases and they were both negative in 83% of non-glandular lesions/cases negative for SIL. Based on this study, both ProExC and IMP3, when used as an immuno panel, can predict the presence of glandular lesions on subsequent biopsies and can serve as an aid in the diagnosis and management of AGUS cases.