No abstract

The proto-oncogene (pleomorphic adenoma gene 1 (PLAG1)) is immunohistochemically overexpressed in pleomorphic adenoma (PA). Its expression in recurrent pleomorphic adenoma (RPA), however, has not been investigated. Since complex mechanisms are involved in tumor recurrence, the aim of this study was to investigate whether PLAG1 overexpression occurs in RPA. We studied PLAG1 protein expression in 40 PAs and 36 RPAs by immunohistochemistry. Cases with immunopositive cells were classified into two categories, between 10 and 50 % and >50 %. In both groups, PLAG1 expression was observed in both epithelial and myoepithelial cells. Of PAs, 37 cases (93 %) were positive, while this was the case in 34 RPA cases (94 %). Our findings suggest that in addition to morphological similarity, PA and RPA express PLAG1, which might play a role in tumor recurrence. Furthermore, as for PA, expression of PLAG1 can be considered a valuable diagnostic marker for RPA.

Pleomorphic adenoma (PA) is the most common salivary gland neoplasm, corresponding to about 60% of all neoplasms. Although most cases are surgically removed by radical resection, recurrences may occur even after several decades and in some cases malignant transformation may still occur of a pre-existing PA causing the carcinoma ex pleomorphic adenoma (CXPA). CXPA, although relatively rare, reserve a poor prognosis and it has an aggressive clinical course. Strong correlation has been described between both neoplasia and the proto-oncogene PLAG1 (Pleomorphic Adenoma Gene 1) which leads to production of a protein that positively regulates several growth factors genes. The PLAG1 expression analysis in both tumors will help in the confirmation this marker for the diagnosis of PA and CXPA, besides of contribute to better understanding of carcinogenesis of CXPA.