Distribution of the extracellular matrix glycoproteins in ependymomas--an immunohistochemical study with follow-up analysis.

The extracellular matrix (ECM) plays a critical role in influencing the biological behavior of brain tumors and the diagnostic detection of ECM components in ependymomas might be of prognostic value. In the present study we evaluated immunohistochemically the expression of a spectrum of ECM glycoproteins (tenascin, vitronectin, fibronectin, laminin, collagen types II, IV and VI) in a series of 36 pediatric intracranial ependymomas. The distribution of the ECM glycoproteins was evaluated both within the tumor tissue and at the tumor invasion front, and the prognostic value of the results was tested in a survival analysis. The expression of most of the ECM glycoproteins was associated only with blood vessels. Tenascin and vitronectin were found in a more diffuse pattern around the tumor cells and at the tumor invasion fronts of several cases. The progression-free survival was significantly decreased for patients with tenascin positive tumors (in any of the studied compartments) and for the tumors with vitronectin accumulation at their invasion fronts. In one ependymoma containing foci of cartilage with metaplastic ossification we demonstrated that collagen types II and VI and tenascin were present in ECM of both the cartilage and the ependymoma, and were accompanied by areas of necrosis and dystrophic calcifications. We suggest, that the rare simultaneous production of the specific ECM components might lead to the formation of chondroid areas in ependymomas. An abundant production of some ECM glycoproteins (tenascin and vitronectin) is present in a proportion of ependymomas and its immunohistochemical detection is of prognostic relevance.