ProEx C Stain Analysis in Recurrent Respiratory Papillomatosis

Abstract

We evaluated the presence and pattern of ProEx C stain, a marker for the proliferative capacity of cells, in laryngeal tissues, including benign, malignant, and recurrent respiratory papilloma (RRP) specimens, and compared it to hematoxylin and eosin staining for the presence of dysplasia. We performed a retrospective study with chart review. A total of 26 specimens (9 benign, 7 malignant, 10 RRP) representing 21 patients were stained. ProEx C stained positive in the nuclei of laryngeal tissue, consistent with its localization in cervical cytology specimens. Seven of 9 benign and 7 of 10 RRP specimens stained positive. The benign specimens were mostly polyps. The malignant specimens were either well or moderately differentiated squamous cell carcinoma, and they stained strongly and diffusely. In benign and RRP specimens, the basal layer typically stained positive. Other areas of epithelium stained weakly in benign specimens and variably in RRP specimens. Current analysis of hematoxylin and eosin-stained RRP specimens revealed that 30% of specimens had at least moderate dysplasia and 80% exhibited viral changes (koilocytosis). ProEx C is a clean and reliable stain in laryngeal tissue, and stains positive in RRP. This study could not definitively correlate positive ProEx C staining in areas of greater dysplasia, although a trend was observed. Further studies are necessary to determine whether ProEx C can be used in triage of cases of clinically aggressive RRP for closer follow-up or frequent operative intervention.