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 restricted expression especially in areas of cell proliferation, cell motility, and tissue modeling at the epithelial-mesenchymal junction during 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 membrane (n = 3). Hyperplastic epithelia in leuoplakia showed a distinct increase in tenascin immunoreactivity in the submucosa correlating with the degree of hyperplasis and/or dysplasia. In squamous cell carcinoma (SCC), the reactivity was most intense extending deeply into the underlying 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 masses in regional lymph nodes. The stromal tissues infiltrated by inflammatory cells were usually unreactive while those with desmoplastic changes were positive for tenascin. The authors conclude that an enhanced expression of tenascin may play an important role during active phases of tumour cell proliferation and stromal changes in the premalignant and malignant lesions of the oral mucosa.