The majority of
thymomas are histologically characterized by tumor-infiltrating lymphocytes. Mature dendritic cells (DCs) are known to assemble lymphocytes through antigen presentation to T lymphocytes.
Fascin, a 55-kDa
actin-binding protein and a known marker for mature DCs, regulates filaments necessary for the formation of filopodia in cell migration. Moreover,
fascin expression in various
epithelial neoplasms has recently been reported to be associated with invasion of
tumor cells and clinically aggressive manifestations. In the present study, we investigated
fascin expression immunohistochemically in tissues of
thymomas and
thymic carcinomas surgically resected at our institute. A total of 34
thymomas and 5
thymic carcinomas were included. The amount and immunohistochemical intensity of both
fascin(+) DCs and
tumor epithelium were counted and assessed, and the clinicopathological data were also scored. Statistical analyses revealed that the amount of
fascin(+) DCs with the formation of clusters was associated with lymphocyte-rich variants (p=0.002) and cortical differentiation (p=0.037) of
thymoma with complication from
myasthenia gravis (p=0.002). The quantity of
fascin(+) epithelium was associated with a strong intensity of
fascin in infiltrating DCs (p=0.002) with the formation of clusters (p=0.002) and favorable prognosis, as assessed by the Masaoka staging system (p=0.001). The amount of infiltrating DCs (p=0.024) and
fascin(+) epithelium were lower in
thymic carcinoma. It was concluded that
fascin(+) epithelium may induce
tumor immunity through the surveillance activity of
fascin(+) DCs in
thymic neoplasms, thus improving prognosis.