Diagnostic and clinical significance of D2-40 expression in the normal human thymus and thymoma.

Human thymus development and thymoma behavior remain elusive, in spite of many acquisitions in the field in last decades. In the present paper, we analyzed the immunohistochemical expression of D2-40 in the normal human thymus and thymoma. In both fetal and postnatal normal thymus, we found a strong expression of D2-40 in the subcapsular and cortico-medullary epithelial cells, and lack of expression in the thymus of involution. These findings support a role for podoplanin in the proliferation of some subtypes of epithelial cells of the normal thymus stroma. In thymoma, the expression of D2-40 was detected in neoplastic cells in 18 from 26 cases (69.23%). No correlation was found between D2-40 expression and histological types of thymoma, but strong correlation was noticed with tumor stage. Based on these results, it is suggested that D2-40 expression is a good predictor of invasion and can be considered as a potential target for therapy in selected cases.