Alterations of the p53 gene are the most frequently documented genetic abnormalities in human cancer. The aim of the present study was to analyse if this alteration is an early event in oral tumorigenesis and if the suprabasal expression of p53 is a marker of the presence and severity of epithelial dysplasia. Immunohistochemical p53 expression in 78 specimens of oral squamous cell carcinoma and non-tumoral adjacent epithelium was analysed. Non-tumoral epithelium was observed in 53 cases (67.9 per cent), being normal in six cases (7.6 per cent), hyperplastic in 24 cases (30.7 per cent) and dysplastic in 48 cases (61.5 per cent). Epithelial dysplasia was mild (23 cases, 47.9 per cent); moderate (23 cases, 47.9 per cent) and severe (two cases, 4.1 per cent). Twenty-one cases of the dysplasias (43.8 per cent) expressed p53. No p53 expression appeared in any normal epithelium. Basal p53 expression always appeared in mild dysplasias (two cases). Suprabasal p53 expression appeared in mild and moderate dysplasias in nine cases and in one severe dysplasia. No statistical correlation was observed between suprabasal expression of p53 and the presence or severity of the dysplasia. The expression of p53 is an early event in oral tumorigenesis but it does not behave as an objective marker of the presence or severity of epithelial dysplasia.

Ameloblastic carcinoma is an unusual tumour. There have been a total of 34 cases of ameloblastic carcinoma in the English literature to date. Of these only 11 cases have occurred in the maxilla. The authors report the 12th such case. The histological classification for odontogenic carcinoma has been debated for many years and recently revised, thus differentiating between malignant ameloblastoma and ameloblastic carcinoma. The authors review the current literature regarding diagnosis and treatment of this unusual lesion, and support the use of the term malignant ameloblastoma for the tumours that metastasize in spite of their benign histological appearance, whereas, the ameloblastic carcinoma is referred to as the primary tumour with malignant transformation, regardless of its metastatic potential.