Immunohistochemical Analysis of the Expression of Cytokeratins in Acquired Cholesteatoma and Its Clinico-Radiological Correlation

Background and Objectives: Cholesteatomatous chronic otitis media acquires epithelial proliferation and differentiation characteristics, which render it able to erode the underlying bone and cause complications. We attempt to characterize the cholesteatoma epithelium by observ-ing the expression of cytokeratins (such as 34 ss e12, CK17, and CK13) and Ki67 among pa-tients with cholesteatoma with different aggressiveness as compared to disease-free controls. Subjects and Methods: In this prospective study (2017-2021), we enrolled all consenting consecutive patients with cholesteatomatous chronic otitis media. They were staged in accor-dance with the staging guidelines of the European Academy of Otology and Neurotology and the Japanese Otological Society. Bony external auditory canal (EAC) skin specimens of the pa-tients undergoing tympanoplasty were chosen as controls. We did an immunohistochemical analysis of the cholesteatoma specimens and normal bony EAC controls by observing the ex -pression of 34 ss e12, CK17, CK13, and Ki67 across the layers of the epithelium. Fisher's exact test and chi-square test were used to evaluate any statistical significance between the cases and the controls, and the subgroups were made based on the clinical stage. Results: An in-creased expression of CK17 (p<0.001), CK13 (p<0.03), and Ki67 (p<0.001) was observed in cholesteatoma specimens when compared to normal bony EAC controls. Also, there was a loss of expression of 34 ss e12 in a subset of cholesteatoma specimens, all of which showed full-thick-ness expression of CK13. There was no difference in the expression of cytokeratin among specimens from patients belonging to different subgroups based on clinical stage, age, sex, du -ration of ear symptoms, or type of hearing loss (conductive vs. sensorineural). Conclusions: The majority of cholesteatoma specimens significantly overexpressed CK17, CK13, and Ki67 when compared to normal bony EAC skin controls, while a subset showed loss of expression of 34 ss e12, which provides some insight into its pathogenesis.

Automated summary

The expression of cytokeratins and Ki67 in the epithelium of cholesteatoma was observed. The results showed increased expression of CK17, CK13, and Ki67, and decreased expression of 34 ss e12 in cholesteatoma specimens compared to normal bony EAC controls. This provides some insight into the pathogenesis of cholesteatoma.