Analysis of p53 Protein by PAb240, Ki-67 Expression and Human Papillomavirus DNA Detection in Different Types of Odontogenic Keratocyst

Objective: To investigate the possible association between alterations in the p53 system and human papillomavirus (HPV) infection in the etiology of odontogenic keratocysts (OKCs) and to study proliferation and epithelial maturation patterns by topographic analysis of Ki-67 expression. Materials and Methods: Eighty-three OKC samples (29 cases associated with nevoid basal cell carcinoma syndrome, 29 solitary non-recurrent cases 20 solitary recurrent cases, and 5 chondroid keratocysts) were studied by immunohistochemistry to detect p53 protein (PAb 244) and Ki-67 (MIB-1) expression, and by PCR to detect HPV DNA. Results: Twelve cases (14.6%) expressed p53 protein; no case showed the presence of HPV DNA; 9 cases (11%) presented with mild epithelial dysplasia. The suprabasal expression of Ki-67 was significantly more frequent than its basal expression (p<0.001). p53 protein expression was significantly associated with the presence of epithelial dysplasia (p=0.023). Ki-67 expression was not associated with OKC type, the presence of dysplasia, or p53 expression. Conclusion: HPVs do not participate in the etiology of OKC, and it appears unlikely that a p53 gene mutation mechanism plays a major role in the genesis of OKC. OKCs show proliferation and genuine maturation behavior reminiscent of benign neoplasms with local destructive capacity. The odontogenic keratocyst (OKC) appears to have an intrinsic growth potential not found in other odontogenic cysts (1-6), characterized by a marked ability for destroying bone and a high tendency for recurrence. OKC is one of the lesions associated with the Nevoid Basal Cell Carcinoma Syndrome (NBCCS), which can also include the presence of multiple basal cell carcinomas and can occasionally undergo malignant transformation (7-9). Some of these features are more in accordance with a neoplastic lesion than with developmental odontogenic cysts (10-14).