Leiomyosarcoma of the kidney: CT and MR appearance.

A case of leiomyosarcoma of the kidney is reported here with its CT and MRI manifestations correlated to the pathologic findings. The leiomyosarcoma appeared as a well-defined multinodular mass of varying density and signal intensity on CT and MRI, respectively. The low signal-intensity regions on T2-weighted MRI exhibited delayed enhancement on CT and contained more fibrous tissues than did other sites that had more spindle-shaped muscle cells. Knowledge of the MR and CT characteristics may permit radiologists to refine the diagnosis of renal leiomyosarcoma considerably.