Stromal characterization and comparison of odontogenic cysts and odontogenic tumors using picrosirius red stain and polarizing microscopy: A retrospective and histochemical study

INTRODUCTION: Odontogenic lesions represent a range of conditions, the features of which probably depend on the stage of induction towards tooth formation reached prior to neoplastic or hamartomatous proliferation. It has been also suggested that inductive changes may allow progression from one type of odontogenic tumor to another. The epithelium also plays an important role in the pathogenesis of these lesions; even stroma is likely to play an equally important role in the pathogenesis and biological behavior. So, this study was performed to investigate, compare, and correlate different types of collagen fibers in odontogenic cysts and odontogenic tumors. MATERIALS AND METHODS: Thirty each pre-diagnosed odontogenic cysts and tumors were histochemically analyzed using a special stain (Picrosirius red stain) and polarizing microscopy. RESULTS: Seven cases (99%) of inflammatory cysts exhibited predominantly greenish-yellow birefringence indicating procollagen, intermediate, or pathologic collagen fibers suggestive of loosely packed collagen fibers. Predominant yellowish-orange birefringence exhibited by 21 cases (99%) of developmental cysts was comparable to the yellowish-orange and orangish-red to red birefringence exhibited by odontogenic tumors suggesting tightly packed fibers. CONCLUSIONS: The Picrosirius red stain in conjunction with polarizing microscopy serves as a specific and sensitive tool in characterizing collagen fibers in odontogenic cysts and odontogenic tumor.