A case of uterine leiomyoma with intravenous leiomyomatosis--histological investigation of the pathological condition--.

Intravenous leiomyomatosis (IVL) is generally defined as a histologically benign leiomyoma derived from a uterine myoma or intrauterine venous wall that has grown and extended intravenously. We here report on a single case of IVL, and investigate its pathological genesis. Regarding the part of the myoma extending to the vessel lumen, observations found the myoma to be pushing into the vessel. Immunostaining with CD34 antibody gave an image of the area where the myoma pushed into the vessel, showing CD34-positive vessel endothelium cells folded back into a layer covering the myoma, and continuing to line of the surface of the myoma within the vessel. Early pathological genesis of IVL was clarified for the first time that the tumor did not invade the vessel by breaking the venous wall, but rather advanced by stretching the vascular wall and progressing into the vein like a polyp, covered in endothelium cells.