Odontogenic keratocyst (OKC) is an aggressive cyst with neoplastic behavior and unicystic ameloblastoma (UA) is a neoplasm with cyst like behavior. Both odontogenic keratocyst and unicystic ameloblastoma show biologic behavior unlike other lesions in their respective groups. In the present study, the biological behavior of these lesions were assessed by studying the collagen fibers in their walls using picrosirius red (PSR) polarization method.

Collagen fibers in 20 cases of OKC and 20 cases of UA were studied histologically by staining sections with picrosirius red dye and examining them by polarizing microscopy. Polarization colors of the collagen fibers of the lesions were recorded according to their width.

While no differences were seen between the polarization colors of thin fibers (< 0.8 μ) in both odontogenic keratocyst and unicystic ameloblastoma, the polarization colors of thick fibers of odontogenic keratocyst were significantly more greenish-yellow as compared to the unicystic ameloblastoma which were predominantly yellowish-red.

These findings suggest that odontogenic keratocyst is a more aggressive lesion than unicystic ameloblastoma by means of identifying abnormally packed collagen fibers in odontogenic keratocyst but not in unicystic ameloblastoma. Thus, the nature of collagen fibers as studied by the picrosirius red polarization method may be useful as a diagnostic tool to differentiate between the two lesions.