Cytokeratin 18 & 19 Expression in Normal Mucosa, Lichen Planus and Squamous Cell Carcinoma

Cytokeratins (CK) are structural proteins in epithelial cells. Changes in cytokeratin expression have been observed during neoplastic transformation. Objectives: To evaluate cytokeratin 18 and 19 expression in normal mucosa, lichen planus and squamous cell carcinoma. Materials and methods: Thirty cases each of normal mucosa, lichen planus and squamous cell carcinoma were retrieved from the archives of the Department of Oral Diagnosis, Khon Kaen University. Tissue sections were stained with antibodies to cytokeratin 18 and 19. Immunoreactivity was evaluated by counting cells. The CK labeling index was calculated by dividing the number of positively stained cells x 100 by total number of cells counted. Results: 9 out of 30 (30.0%) normal mucosa, 5 out of 30 (16.7%) lichen planus and 4 out of 30 (13.3%) squamous cell carcinoma demonstrated positive staining for CK18. Squamous cell carcinoma showed the highest mean CK18 labeling index, followed in descending order by normal mucosa and lichen planus, respectively. Twenty three out of 30 (76.7%) normal mucosa, 9 out of 30 (30.0%) lichen planus and 1 out of 30 (3.33%) squamous cell carcinoma elicited positive staining for CK19. Normal mucosa elicited the highest mean CK19 labeling index, followed in descending order by lichen planus and squamous cell carcinoma, respectively. Conclusions: CK18 expression in normal mucosa, lichen planus and squamous cell carcinoma is low and there is no statistical difference among the three groups of lesions. CK 19 expression in normal mucosa is statistically higher than that of lichen planus and squamous cell carcinoma. CK19 might be a good candidate to be included in a panel of antibodies for detecting malignant transformation of oral mucosa into squamous cell carcinoma.