14534 Background: Adrenocortical carcinoma (ACC) is a very rare disease which account for no more than 0.2% of all malignancies, and its differential diagnosis from adrenocortical adenomas (ACA) is based on the application of different scoring systems, which, however, lack a sensitivity and specificity of 100%. Little is known on the mechanisms leading to the malignant phenotype in adrenocortical tumors; among alternative mechanisms, metalloproteinases (MMPs) have been demonstrated in solid tumors, including endocrine ones, to be implicated in malignant progression and metastatization. Our aim was to investigate metalloproteinase 2 (MMP2) expression in adrenocortical tumors. Methods: A series of 33 ACC and 23 ACA was retrospectively collected from a large series of adrenocortical lesions, and the diagnosis was reviewed independently by three investigators (MV, EB, MP) according to the Weiss histological criteria. MMP2 was determined by immunohistochemistry and the results scored by semi-quantitative analysis, based on the intensity of the staining and the percentage of tumor cells positive. Immunohistochemical results were compared to clinico-pathological parameters, such as sex, age, hormonal secretion, and outcome. Results: MMP2 expression was detected in 1/23 ACA (4%), and in 25/33 ACC (76%) (X-square test p < 0.001). MMP2 immunohistochemical pattern in ACC was focal to moderate to strong in 10, 12 and 3 cases, respectively. In addition, moderate to strong MMP2 expression, as compared to low or negative immunostaining, correlated with shorter disease-free survival (p = 0.012) and poor outcome (p = 0.07). No correlation were found comparing MMP2 expression and other clinico-pathological parameters. Conclusions: As reported in a variety of solid tumors, our data indicates a possible role of MMP2 in the malignant evolution of adrenocortical tumors, and its immunohistochemical localization may be a potential useful tool in the differential diagnosis of benign versus malignant adrenocortical lesions. In addition, a strong immunohistochemical MMP2 expression seems to be related to a poor prognosis in ACC. No significant financial relationships to disclose.
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