HEMANGIOSARCOMA OF THE BREAST—CASE REPORT WITH SCANNING ELECTRON MICROSCOPIC STUDY—

Hemangiosarcoma of the breast in a 22‐year‐old female was presented. She died of massive pulmonary metastasis and apparent internal hemorrhage from the involved liver by metastasis after 40 months of the illness. Intense scanning electron microscopic (SEM) study was undertaken on this lesion. At the same time, in order to compare SEM findings of angiosarcoma with several other benign disorders, the following lesions were chosen, namely, chronically‐inflamed veins in the gastric submucosa, benign cavernous hemangiomas of the skin and liver, and organizing thrombi with papillary structures. Some of these lesions exhibited focal similarities in surface structures to those from angiosarcoma. Besides various characteristics by SEM in angiosarcoma, cell clusters protruding into the vascular cavity were found to be the most unique feature which we have never observed in any other lesions.