Maturation of Wilms' tumor pulmonary metastases to benign fibromas after therapy.

A 3-year-old girl with Wilms' tumor developed pulmonary metastases 5 months after diagnosis. All but one of the visible lesions disappeared after thoracic irradiation and multiple-agent chemotherapy. Subsequent thoracotomy revealed 17 small nodules in addition to the visible lesion, and all of them proved to be fibromas. It would appear that the Wilms' tumor metastases to the lung were made to mature to benign neoplastic processes after the treatments given.