Leiomyoma of the kidney: presentation of 4 new cases and the role of computerized tomography.

Renal leiomyoma is a challenging diagnostic and therapeutic condition. It is clinically similar in presentation and radiographic appearance to its malignant counterpart, leiomyosarcoma. We review 30 cases of clinically diagnosed leiomyoma of the kidney from the literature, including 4 new cases with emphasis on the computerized tomography findings. Computerized tomography may locate a renal leiomyoma serendipitously in an asymptomatic patient. If the lesion is peripheral or in the parapelvic area and a plane can be seen between the tumor and kidney a capsular tumor, such as a leiomyoma of the kidney, might be considered in addition to the more common renal cell carcinoma. Renal leiomyomas have a variable radiographic pattern from that of a pure cystic to a mixed solid/cystic to an entirely solid lesion. Renal leiomyomas usually are sharply demarcated from the surroundings. Although computerized tomography cannot distinguish a renal leiomyoma from other benign or malignant renal processes the presence of invasion can virtually eliminate this benign tumor as a diagnosis. Since a preoperative diagnosis cannot be made, management involves renal exploration and radical nephrectomy in the larger lesions with a renal-sparing operation possible in selected cases. After treatment patients have a uniformly excellent prognosis.