Adenomatoid odontogenic tumour: hamartoma or neoplasm? A contribution to debate.

This study aimed at understanding the biological and cellular mechanisms in this tumour. Eight formalin fixed paraffin embedded blocks of AOT were studied by immunohistochemical staining for proteins p63 and Ki-67 using the System EnVision System™ (Dako Cytomation, Glostrup, Denmark). The analysis was performed considering the distribution of immunoreactivity, and using scores: - (0 to 5% of positive cells); +1 (6-25% positive cells) +2 (26-50% positive cells); 3 + (> 50% positive cells). All the 8 cases examined were positive for proteins p63 and Ki-67. Expression of p63 protein was intensive and involved all cell groups, whereas Ki-67 was predominantly detected in cubic cells lining the duct-like structures. The results suggest that the intense immunostaining of p63 protein reflects the low degree of differentiation of the AOT cellular components and contributes to cellular and architectural heterogeneity observed in this tumour. Besides, expression of the Ki-67 protein suggests that cell proliferation in the AOT is low, which explains the benign biological behavior of the tumour. The findings of this study indicate the AOT as a true neoplasm with low proliferative cell index.
Source: Head and Neck Oncology - Category: Cancer & Oncology Source Type: research