Cytopathological Features of a Severe Type of Corneal Intraepithelial Neoplasia

PURPOSE: To report the cytopathological features of corneal intraepithelial neoplasia (CIN) through the investigation of cytokeratin expression pattern, keratinization, cell proliferation, apoptosis, and epithelial mesenchymal transition. PATIENT AND METHODS: Corneal tissue excised from a CIN patient was examined in this study. Cryosections of the excised CIN epithelial tissue were examined by immunostaining analysis using antibodies against cytokeratins, keratinization-related proteins, Ki-67, human telomerase reverse transcriptase (hTERT), and epithelial mesenchymal transition (EMT)-related proteins. Subcellular localization of F-actin was also analyzed using phalloidin. For the detection of apoptotic cells, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay was performed. Real-time polymerase chain reaction was performed to quantify the expression level of hTERT in the CIN epithelium. RESULTS: The CIN epithelium exhibited a significantly altered cytokeratin expression pattern compared to normal corneas with an upregulated expression of keratinization-related proteins. The CIN epithelium also demonstrated an increased number of Ki-67-positive cells with an upregulated expression of hTERT, while exhibiting an increased number of apoptotic cells. EMT did not occur in the CIN epithelium. CONCLUSION: CIN epithelium seems to be slightly dedifferentiated from the corneal epithelial lineage. The status of cell proliferation and apoptosis in the CIN epithelium was significantly altered from that of normal corneal epithelium, but its malignancy level does not appear to be as high as that of metastasis-competent malignant cancers.