Image Description
Primary Leiomyosarcoma of Kidney: Microscopic features are similar to leiomyosarcomas seen at other sites. The tumor is composed of intersecting fascicles of eosinophilic spindle cells with cigar-shaped blunt-ended nuclei. Nuclear pleomorphism, increased mitotic activity, vascular invasion, and myxoid change are additional features. Positive immunohistochemical markers include smooth muscle actin, desmin, vimentin, calponin, and h-caldesmon. Negative markers include cytokeratin, myogenin, CD117, CD34, HMB45, Melan A, and S100 protein.