Proliferative potential and cell kinetics of ameloblastoma and malignant ameloblastoma were studied by immunohistochemical staining with monoclonal anti-PCNA antibody (PC10. Novocastra).
In this study, 18 primary, 6 recurrent and 2 malignant ameloblastomas were used. Anti-PCNA antibody was labelled in proliferating cells in all the cases. In primary ameloblastomas, the labelling indices showed no significant difference between follicular (mean 13.1%) and plexiform type (15.9%) of ameloblastomas. However, the distribution pattern of PCNA-positive cells in follicular ameloblastomas was different from that of plexiform type: In the former, only peripheral tumor cells of tumor parenchyma were positive for and-PCNA, but in the latter, PCNA-positive cells were diffusely distributed in tumor parenchyma.
In recurrent ameloblastomas, it was noted that PCNA positive rate was higher (22.2%) than that of primary lesions (13.8%).
Malignant ameloblastomas showed that the growth fractions were remarkably higher (43.3%) than primary ameloblastomas. The results of this study clearly show that recurrent ameloblastomas have high proliferating potential in comparison with primary lesions. Moreover, it is suggested that when it is difficult to distinguish between ameloblastomas and malignant ameloblastomas under light microscopy, PCNA immunostaining is useful to differentiate them.