Clinical and Pathological Significance of <scp>GLUT</scp> ‐1 Expression in Angiosarcoma and Other Vascular Tumors

Vascular anomalies are classified according to the ISSVA classification into vascular tumors with endothelial proliferation and vascular malformations without proliferation. Infantile hemangioma is a vascular tumor that is diagnosed by GLUT-1 immunoreactivity. GLUT-1 positivity is reportedly sometimes observed in angiosarcoma, but the clinical significance remains unclear. Here, immunohistochemistry was performed on tissue samples from patients with angiosarcoma (n = 10), pyogenic granuloma (n = 9), and senile hemangioma (n = 10), with infantile hemangioma serving as a positive control. GLUT-1 expression was detected in the cytoplasm and/or cell membrane of tumor cells in all cases of angiosarcoma (100%), as well as in the cytoplasm of some cases of pyogenic granuloma (44.4%) and senile hemangioma (40%). Double immunofluorescent staining for GLUT-1 and CD34 revealed co-expression in tumor endothelial cells of angiosarcoma. Clinically, cases of angiosarcoma with strong membranous GLUT-1 expression tended to be associated with tumor progression, while those with weak or mild cytoplasmic expression showed a better response to treatment. These findings suggest that GLUT-1 may serve as a useful marker of tumor progression for angiosarcoma, and as a potential therapeutic target in vascular tumors.