TENASCIN IMMUNOREACTIVITY IN LUNG-TUMORS

The distribution of tenascin immunoreactivity was analyzed in nonneopl astic lung tissue, benign lung tumors, and different types of lung car cinomas. In nonneoplastic lung tissue, tenascin could be observed in t he basement membranes of the bronchial epithelium and endothelial cell s, smooth muscle cells, and bronchial cartilage. Strong tenascin immun oreactivity was seen in the stroma of all the carcinomas of various hi stologic types. The staining intensity was stronger in the stroma of s quamous cell carcinomas than in the stroma of the other types of lung carcinomas. In 10 of 27 squamous cell carcinomas, a granular intracyto plasmic reactivity could also be observed in a subpopulation of tumor cells. Similar intracytoplasmic reactivity was observed in 2 of 27 ade nocarcinomas and in both adenosquamous carcinomas. In other types of l ung tumors, individual cells did not have intracytoplasmic tenascin, e xcept for one case of leiomyoma, which showed a weak, linear, intracyt oplasmic tenascin reactivity. In lung hamartomas, tenascin could be se en in the cartilaginous component of the tumor and in the areas of bas ement membranes of the bronchial epithelium. In the carcinoid tumors, the stroma displayed a faint positivity for tenascin. These results sh ow that tenascin is widely expressed in the stroma of lung carcinomas. A proportion of lung carcinomas also expressed intracytoplasmic tenas cin immunoreactivity, suggesting that tumor cells may be able to synth esize tenascin. In the lung, tenascin positivity is not, however, rest ricted to malignant neoplasms, as evidenced by the presence of tenasci n in nonneoplastic lung parenchyma and in some benign lung tumors.