Frequently, diagnosis of lichen planus as a relative common chronic inflammatory mucocutaneous disease, is difficult, therefor, direct Immunofluorescence (DIF) examination is recommended for definite diagnosis. In this study both an statistical analysis of files of oral and maxillofacial pathology department of Dentistry school and direct immunofluorescence examination using paraffin blocks with new method, were performed. According to analysis of 8026 cases, 262 (3.26%) cases were diagnosed as lichen planus; most patients were in fourth decade of their life and most common affected region was buccal mucosa, (69.68%).
In direct immunofluorescence study of 14 cases (using firth's method) fibrinogen deposits in 6 cases and immunostaining of colloid bodies with various immunoglobulins (IgA, IgG, IgM), C3 and also fibrinogen (few values) in most of patients, were detected. In spite of the fact that density of staining was lower than routine method (using fresh-frozen tissue), except for fibrinogen immunostaining, these findings are compatible with previous studies. In spile of limitation of samples, this study suggests that using this technique needs more evaluation and this can be used for diagnosis purposes when fresh-frozen tissue is unavailable.