IMMUNOREACTIVE TENASCIN IN TUMORS OF SALIVARY-GLANDS - EVIDENCE FOR ENHANCED EXPRESSION IN TUMOR STROMA AND PRODUCTION BY TUMOR-CELLS

Tenascin, a large molecular weight extracellular glycoprotein expresse d at the epithelial-mesenchymal interface during morphogenesis in embr yo, wound healing and in the stroma of various benign and malignant tu mours was evaluated in a series of primary epithelial tumours of saliv ary glands using a monoclonal antibody. Normal salivary glands (n=5) h ad linear delicate band-like immunoreactive tenascin in relatively lar ge excretory or intralobular ducts. Pleomorphic adenomas (n=40) had he terogeneity of expression in modified myoepithelial cell-associated my xoid, hyaline and chondroid areas. Warthin's tumours (n=10) had a line ar immunoreactivity profile of tenascin just adjacent to the basal cel ls of the epithelial tumour component. A heterogeneity of expression w ith intense to low or negative stromal immunoreactivity was observed i n adenoid cystic carcinomas (n=8), mucoepidermoid carcinomas (n=8), ep ithelial-myoepithelial carcinomas (n=4), polymorphous low-grade carcin omas (n=3), papillary cystadenocarcinomas (n=15) and undifferentiated carcinomas (n=3). In addition, small cystic spaces or lumens of epithe lial-lined tubulo-ductal structures in numerous salivary tumours had p ositive immunoreactivity for tenascin, suggesting its production by th e epithelial tumour component. An enhanced expression of tenascin in s alivary tumours suggests a role of this protein in the stromal remodel ling and tumour growth.