Type IV collagen, the major component of basement membrane (BM), demonstrates a stage- and position-specific distribution of its isoforms during tooth development. To determine its localization in BM of malignant odontogenic neoplasms, immunohistochemistry using six anti-alpha(IV) chain-specific monoclonal antibodies was performed. Results disclosed that BM demonstrated an irregular alpha(IV) chain profile in tooth germ as compared to benign odontogenic neoplasms. No alpha3(IV) chains were detected. Expression of alpha1(IV)/alpha2(IV) and alpha4(IV), alpha5(IV)/alpha6(IV) chains was ameloblastic fibro-odontosarcoma, but not the inductive hard tissues. Ameloblastic carcinoma showed specific alpha1(IV)/alpha2(IV) chain loss, while primary intraosseous carcinoma demonstrated a discontinuous alpha1(IV)/alpha2(IV) and alpha5(IV)/alpha6(IV) staining pattern. The present results suggest that modification and remodeling of BM collagen IV alpha chains occur during malignant odontogenic neoplasms' progression.
