perithelioma (per"e-the-le-o'mah)

A tumor composed of capillaries running in various directions lined with endothelioma and surrounded by a ma of cells many layers deep and radially arranged. These cells spring from the per it helium which lines the per i vascular spaces of blood ve els. [Gr., peri, around, -fthele, the nipple, + oma, a tumor.] per it helium (per-e-the'le-um). tial or complete sheath of a The par capillary, small artery, or vein, formed by the branched cells of the surrounding areolar or adenoid ti ue, the branched cells being in intimate connection with the cells forming the proper wall of the ve el; also, one of those branched cells. [Gr., peri, around, + thele, a nipple.]