ENHANCED TENASCIN IMMUNOREACTIVITY IN LEUKOPLAKIA AND SQUAMOUS-CELL CARCINOMA OF THE ORAL CAVITY - AN IMMUNOHISTOCHEMICAL STUDY

Tenascin is an extracellular matrix glycoprotein that shows a site res tricted expression especially in areas of cell proliferation, cell mot ility, and tissue modeling at the epithelial-mesenchymal junction duri ng embryogenesis. Tissue specimens obtained from surgery and/or biopsy for oral leukoplakia (n=22) and squamous cells carcinoma (n=36) were examined for the presence of tenascin by using monoclonal antibody. In normal tissue specimens (n=5), tenascin immunoreaction appeared as a linear continuous lining at the immediate vicinity of basement membran e (n=3). Hyperplastic epithelia in leuoplakia showed a distinct increa se in tenascin immunoreactivity in the submucosa correlating with the degree of hyperplasis and/or dysplasia. In squamous cell carcinoma (SC C), the reactivity was most intense extending deeply into the underlyi ng stroma with marked reaction around large tumour cell nests and the infiltrating tumour margin. The connective tissue stroma, however, in undifferentiated carcinoma showed traces of immunoreactivity. Positive immunoreactivity was seen around metastatic squamous cell carcinoma m asses in regional lymph nodes. The stromal tissues infiltrated by infl ammatory cells were usually unreactive while those with desmoplastic c hanges were positive for tenascin. The authors conclude that an enhanc ed expression of tenascin may play an important role during active pha ses of tumour cell proliferation and stromal changes in the premaligna nt and malignant lesions of the oral mucosa.