Patrick Kennedy, the youngest son of Sen. Edward Kennedy, D-Mass., walked out of Massachusetts General Hospital in Boston with a cane Saturday morning after successful surgery to remove a benign growth on his spinal cord. Wearing a neck brace, a pale Patrick, 20, spoke briefly with reporters as he left the hospital accompanied by his father and brother, Edward Jr., 26. "It's been a long ordeal, but I'm very thankful to the doctors and nurses at Massachusetts General Hospital, which is known worldwide for its excellence. And I can attest to that," Patrick said after his father helped him down the steps. "I'm especially appreciative of all the visitors who came by, including Cardinal (Bernard) Law, and for everyone's thoughtful words and prayers," Patrick said. Sen. Kennedy said he hoped Patrick would soon return to his studies at Providence College, where he is a sophomore.