Immunohistochemical Assessment of Proliferating Cell Nuclear Antigen Protein Expression in Plaque, Reticular and Erosive Types of Oral Lichen Planus

Background: Proliferating cell nuclear antigen (PCNA) is a nuclear protein synthesized in the late G1 and S-phase of the cell cycle. Immunodetection of this protein represents a useful marker of the proliferation status of lesions. Aims: The aim of this study is to evaluate the immunohistochemical expression of PCNA in oral lichen planus (OLP) and to assess the PCNA expression in a different layer of epithelium in different types of OLP. Subjects and Methods: A total of 96 cases of histologically proven OLP, 32 cases each of erosive, reticular and plaque type were selected. Two sections were taken from each one for H and E. Other sections were stained according to super sensitive polymer horseradish peroxidase method for identifying PCNA expression. Results: Of the three types of OLP, erosive type showed higher expression of PCNA (average 66.8%, minimum of 55% and maximum of 80.3%) followed by reticular (average 37.7%, minimum of 26% and maximum of 47%) and plaque type (average 17%, minimum of 5% and maximum of 25%) indicating increased proliferative activity. The erosive type also showed higher expression of PCNA in all the layers of epithelium followed by reticular and plaque type. Conclusion: PCNA is a good marker to indicate proliferation status of disease. Out of three types, erosive type possess more proliferative ratio, chances of malignant changes is more in this type.