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 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 malignant
odontogenic tumors as compared to benign odontogenic
neoplasms. No alpha3(IV) chains were detected. Expression of alpha1(IV)/alpha2(IV) and alpha5(IV)/alpha6(IV) chains was stronger in desmoplastic ( n=3) than in ordinary (n=5)
ameloblastomas. The
adenomatoid odontogenic tumor ( n=2) distinctly expressed these chains in BM of cribriform areas and hyaline materials (which was also alpha4(IV)-positive), but weakly around epithelial whorls/rosettes/nests and mineralized foci. These five chains also stained BM and
tumor cells of ameloblastic
fibroma ( n=3) and ameloblastic fibro-odontosarcoma (n=1), but not the inductive hard tissues. Ameloblastic
carcinoma ( n=2) showed specific alpha1(IV)/alpha2(IV) chain loss, while primary intraosseous
carcinoma ( n=1) 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 IValpha chains occur during odontogenic
neoplasms' progression.