Immunocytochemical detection of hMSH2 and hMLH1 expression in oral melanoma

Background: The DNA mismatch repair system (MMR) plays an important role in the maintenance of genomic stability. To date few studies have been perfor med on hMSH2 and hMLH1 expression and melanoma of the head and neck region. A study of two cases revealed no mutations of the mismatch repair genes hM SH2 and hMLH1. Materials and Methods: To verify the possibility of implicat ion of hMSH2 and hMLH2 alterations in melanocytic cancerogenesis, the autho rs examined the protein expression pattern of hMSH2 and hMLH1 by immunohist ochemistry in 9 paraffin-embedded oral melanoma. Results: One case (11%) sh owed nuclear positivity for hMSH2, 3 cases (33%) showed cytoplasmic positiv ity, and five cases (55%) showed no staining in the tumoral cells, even if normal squamous epithelium available in this section showed a nuclear posit ivity. Four cases (44%) showed no hMLH1 staining in the tumoral cells, even if normal squamous epithelium available in this section showed a nuclear p ositivity. Two cases (22%) showed nuclear positivity, and three cases (33%) showed cytoplasmic positivity. Conclusions: The analysis of mismatch repai r genes can be a new molecular diagnostic tools for the detection of patien ts at high risk of developing melanoma and other neoplasia, or metastasis a nd recurrences.