<oncology, tumour> A tumour (usually benign) which is formed from tissues of the endothelium. ... (09 Oct 1997) ... 
(en″do-the″le-o´mә) a tumor arising from the endothelial linings of blood vessels.
Type: Term Pronunciation: en′dō-thē′lē-ō′mă Definitions: 1. Generic term for a group of neoplasms, particularly benign tumors, derived from the endothelial tissue of blood vessels or lymphatic channels; endotheliomas may be benign or malignant.
endothelioma 1. A tumor of the cells that line internal body surfaces. 2. A tumor (usually benign) which is formed from tissues of the endothelium (layer of epithelial cells that lines the cavities of the heart and of the blood and lymph vessels and the serous cavities of the body).
a tumor originating from the endothelium.