Figure 3

Microscopic pathology photographs of primary right atrial angiosarcoma. A. Histologic photomicrograph (HE stain, original magnification 20×); the tumor consists of spindle-shaped cells with pleomorphic nuclei lining anastomosing vascular spaces. Mitotic figures and areas of hemorrhage and necrosis can also be found. These findings support the diagnosis of angiosarcoma. The lower left corner shows myocardial invasion with tumor cells. B. Immunohistochemistry photomicrograph (CD31 stain, original magnification 40×); the tumor cells are positive for the endothelial marker CD31, which confirms the vascular nature of the tumor.