Odontogenic tumors: a study of 340 cases in a Brazilian population.

BACKGROUND: The aim of this study was to determinate the relative frequency of odontogenic tumors (OTs) in a Brazilian population and to compare this data with previous reports. METHODS: We reviewed the achieves of 19 123 specimens from oral pathology laboratory of Universidade Federal de Minas Gerais, from 1954 to 2004. Using the criteria of histologic typification published by the World Health Organization in 1992, we classified the OTs. RESULTS: A total of 340 OTs were found. The frequency of OTs comprises 1.78% of all pathologic specimens in our laboratory. The most frequent tumor was ameloblastoma (45.2%), followed by odontomas (24.91%), and myxomas (9.1%). CONCLUSIONS: Odontogenic tumors are uncommon lesions in this Brazilian population and malignant OTs are very rare. The relative frequency of various types of OTs, age, and gender distribution are similar to those reported in African, Asian but not to Chilean and North American series.

Expression of hMSH2 protein of the human DNA mismatch repair system in oral lichen planus.

Lichen planus is a mucocutaneous disease of inflammatory nature and unknown etiology. It is characterized by a cell-mediated immunological response to induced antigenic change in skin and/or mucosa. The possible malignant transformation of lichen planus remains a subject of controversial discussions in the literature. hMSH2 is one of the human DNA mismatch repair (hMMR) genes and it plays an important role in reducing mutation and maintaining genomic stability. hMSH2 alterations have been reported in oral squamous cell carcinoma and there are evidences suggesting the association between oral lichen planus and squamous cell carcinoma. In this study, we aim to investigate the immunolocalization of hMSH2 protein in oral lichen planus compared to oral normal mucosa epithelium. We examined the expression of hMSH2 protein by immunohistochemistry in twenty-six cases of oral lichen planus. Clinically, 12 of them were categorized into reticular subtype and 14 were atrophic/erosive. Ten cases of normal mucosa were added to the control group. Results showed that the percentage of positive cells to hMSH2 was smaller in reticular (46.54%; p=0,006) and atrophic/erosive (48.79%; p=0,028) subtypes of oral lichen planus compared to normal mucosa (61.29%). The reduced expression of hMSH2 protein in oral lichen planus suggests that this lesion is more susceptible to mutation and therefore facilitate the development of oral squamous cell carcinoma.

Immunolocalization of interleukin 4, interleukin 6, and lymphotoxin alpha in dental granulomas.

OBJECTIVE: The purpose of this study was to determine the immunolocalization of the interleukin (IL) 4, IL-6, and lymphotoxin (LT) alpha in dental granulomas and correlate their expression with the intensity of the inflammatory infiltrate. Study design Fifteen paraffin specimens of dental granulomas were selected, and the streptavidin-biotin complex stain was used to detect IL-4, IL-6, and LT-alpha. RESULTS: Our results revealed a significant statistical correlation between the intensity of inflammatory infiltrate and the percentage of mononuclear cells positive for IL-4. Moreover, we observed a statistically significant correlation between the frequency of cells expressing IL-6 and LT-alpha. CONCLUSION: These data suggest that the predominance of a helper T cell subtype 2 response in dental granulomas is correlated with the exacerbation of the inflammatory reaction and its evolution. Moreover, a correlation between the frequency of IL-6-positive and LT-alpha-positive cells suggests that the synergistic activities of these 2 cytokines may be involved in the pathogenesis of this inflammatory condition.