Tokyo ? A kidney containing a tumor was transplanted from a mother to her son in September, with the son agreeing to the operation after being warned about the risks by Akita University Hospital, it was learned Saturday.

The hospital determined the tumor was benign after the transplant.

The Health, Labor and Welfare Ministry is expected to ban diseased kidney transplants this summer after Uwajima Tokushukai Hospital in Ehime Prefecture was found to have transplanted diseased organs in November.

However, as the ban does not cover kidneys suspected of containing tumors, this latest case is expected to spark debate on whether such organs should be used.