Background: Congenital mesoblastic nephroma (CMN) is generally considered to be a benign neoplasm requiring only total excision. Rare local recurrences have usually been related to incomplete removal, and distant metastases to the lung have been reported three times.
Methods: The authors reported the first case of CMN metastatic to the brain, illustrating a comparison of the histopathology of the primary and secondary lesions.
Results: The gross appearance of the renal tumor was that of a benign CMN. On histopathologic examination, there was a single nodule of more cellular tissue with focal necrosis. This area was diagnosed as within the designation "cellular" mesoblastic nephroma. The appearance of the brain metastasis corresponded to that of the cellular nodule.
Conclusions: This report expands the spectrum of metastatic potential of CMN. Though a rare event, this case underscores the need for close follow-up of infants with CMN.