Clinical and Pathological Significance of GLUT ‐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.