Intermediate filament typing in tumour diagnostics--an aid in histogenetic classification?

It is commonly accepted, that a histogenetic correlation can be established between tumour and mother tissue by means of intermediate filament typing. Recent results concerning the co-expression of different intermediate filaments within one cell, the occurrence of epithelial-specific intermediate filaments in soft tissue tumours, and the modulation of intermediate filament type expression caused by some bioactive substances and viral infections cast doubts on the general acceptance of the histogenetic classification of human tumours by intermediate filament typing. Its characterization determines only the actual morphological differentiation of the neoplastic cells and represents a valuable tool for the diagnostic assessment of the tumour under the viewpoint of the functional differentiation of its cells. A doubtless conclusion concerning the mother tissue of the neoplasia (histogenetic origin) is therefore not possible.