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 observing the expression of cytokeratins (such as 34ße12, CK17, and CK13) and Ki67 among patients 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 accordance 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 patients undergoing tympanoplasty were chosen as controls. We did an immunohistochemical analysis of the cholesteatoma specimens and normal bony EAC controls by observing the expression of 34ße12, 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 increased 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 34ße12 in a subset of cholesteatoma specimens, all of which showed full-thickness 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, duration 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 34ße12, which provides some insight into its pathogenesis.