A case of metastatic brain tumor in the perfusion territory of superficial temporal artery-middle cerebral artery anastomosis

Background: We report a rare case of metastatic tumor in the perfusion territory of superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis. Case Description: A 63-year-old man, who had undergone left STA-MCA anastomosis in the treatment of occlusion of internal carotid artery 4 years ago, presented with a hyperintense lesion on T2-weighted image in the left frontal lobe, the perfusion territory of the prior bypass. Follow-up magnetic resonance imaging 1 month later showed enhanced tumor within the T2 hyperintense lesion. A total removal of the tumor through another craniotomy was performed. The pathologic diagnosis was metastatic carcinoma. Conclusion: This is the first report of the metastatic carcinoma by seeding of tumor cells through STA-MCA bypass flow.