Objective: To investigate the activities of bone resorption related cytokines at the capsule wall of the keratocystic odontogenic tumor (KCOT) by histochemical and immunohistochemical double staining for tartrate-resistant acid phosphatase staining (TRAP), receptor activator of nuclear factor-kappaB ligand(RANKL), osteoprotegerin(OPG), interleukin1alpha(IL-1alpha)and parathyroid hormone-related protein (PTHrP).
Methods: Twenty paraffin blocks of KCOT were sectioned in sequence into five slices. One slice was stained with hematoxylin and eosin to confirm pathological diagnosis. Each of other four slices was histochemically and immunohistochemically double stained separately by TRAP with RANKL, TRAP with OPG. TRAP with IL-1alpha and TRAP with PTHrP to observe expressions of these factors in KCOT.
Results: TRAP positive expression was shown in 10 cases. Positive expression of both TRAP and RANKL were detected in 5 cases. RANKL positive staining mainly scattered in fibrous connective tissue, blood vessels and epithelium was shown in 12 cases. OPG positive staining was detected in 4 cases. IL-1alpha positive cells were also observed in 10 cases and PTHrP positive cells were seen in 6 cases. The TRAP and RANKL positive cells were scattered within the connective tissues near the bone. The IL-1alpha positive staining cells were observed both in epithelium and connective tissues, but predominately in the former.
Conclusion: The mechanism of osteoclastogenesis of KCOT may also be mediated by osteolytic factors such as RANKL, IL-1alpha and PTHrP. These factors involved in the activation and differentiation of pre-osteoclasts to form osteoclasts, thus finally resulted in jaw bone resorption.