STUDIES OF THE INFLAMMATORY PROCESS AND MALIGNANT POTENTIAL OF ORAL MUCOSAL LICHEN-PLANUS

Oral mucosal lichen planus (OMLP) is a well recognized mucosal disease with unknown aetiology. Considerable controversy exists as to whether OMLP is intrinsically premalignant, or if the disorder facilitates th e development of oral mucosal squamous cell carcinoma (OMSCC) by exter nal factors. The aim of the present studies was to investigate the exp ression of c-erbB-2 protein in the keratinocytes of the initial biopsi es of oral mucosal disorders diagnosed as OMLP with no evidence of epi thelial dysplasia and to compare the results with the expression of c- erbB-2 protein in subsequent biopsies obtained from the same patients. These results were compared with the findings from another 26 biopsie s from patients with OMLP and control groups (patients with dysplasia with no evidence of OMLP, patients with OMSCC with no evidence of OMLP and normal oral mucosa). The expression of the c-erbB-2 protein was e valuated by immunohistochemical staining of the gene product with the avidin-biotin-complex method using both fresh frozen and paraffin-embe dded tissue sections. Five of the initial biopsies from patients with OMLP expressed the c-erbB-2 protein and one did not. None of the OMLP cases that subsequently showed evidence of dysplasia expressed the c-e rbB-2 protein and of the OMSCC specimens from the patients with OMLP, 2 were negative and 1 expressed c-erbB-2 protein. Within the other gro up of OMLP specimens 3 (3/26) were negative for c-erbB-2 staining. The specimens from the control groups all expressed the c-erbB-2 protein. The results indicated the probability of the absence of c-erbB-2 stain ing being an indication of a potential for neoplastic transformation i n OMLP with dysplastic changes.