Odontogenic myxoma--characterisation of the extracellular matrix (ECM) of the tumour stroma.

In order to elucidate the origin of the odontogenic myxoma, the composition and the structural organisation of the extracellular matrix (ECM) of this tumour were characterised. Collagen type I, VI, procollagen type III, undulin, tenascin and fibronectin were demonstrated in biopsy material of 4 cases by polyclonal antibodies. The tumour stroma showed a pronounced reaction for collagen type I. Fibroblasts displayed an intense intracytoplasmatic reaction for procollagen type III, and collagen type I was not found in the fibroblasts of the adjacent normal oral mucosa. In contrast to the surrounding connective tissue, label for collagen type VI was weak, as was the reaction for fibronectin and tenascin. Undulin was almost undetectable. The immunohistochemical results suggest that the odontogenic myxoma is characterised by an as yet unobserved structural organisation of ECM proteins, a secretion defect of fibrillar collagens type I and III with no resemblance to physiological tooth development.