It’s hard to say how much longer 2-year-old Sam Lee will live — he has a rare skeletal disorder and an inoperable brain tumor — but his parents are determined to make the most of whatever time he may have left.

That’s why Michael Lee and Erin Benson of James Island are planning once-in-a-lifetime trips for their only son — a trip to New York City to wander around the Sesame Street set and visit dinosaur bones at the Natural History Museum, and a trip to Atlanta to see the whale sharks at the Georgia Aquarium.

“He’s been cosmically unlucky,” said Michael Lee, a communications professor at the College of Charleston.

Lee’s wife, Erin Benson, was admitted to the Medical University of South Carolina this summer to deliver the couple’s identical twin girls when they decided Sam needed to be checked by a pediatrician.

Sam already had been diagnosed with Ollier Disease, a rare bone disorder that affects about one in every 150,000 children, and had undergone multiple operations since he was born because of it.

But they started to notice other strange symptoms. He was having trouble walking and he wasn’t smiling when he laughed, his dad said.

The twins, Ada and Mae, were born Aug. 6, just days after an MRI determined that Sam had a brain tumor. His doctors have deemed it inoperable.

Sam recently finished a round of radiation, but there is little hope that the treatment will curb the tumor’s growth. At best, it may delay the inevitable, Lee said.

“The radiation works in a sense that it forestalls the ultimate end,” he said. “How long it forestalls that is a question. It could be not a very long amount of time. It could be a year, it could be a little longer.”

Lee’s cousin, Brian Moore of Vail, Colo., is hosting a benefit for the family on Thursday.

Moore, a chef, is in Charleston this week to cook a four-course dinner at the Sunrise Cafe on Johns Island. Tickets to the event are $60, and all the proceeds will be donated to the Lee family to help pay for Sam’s trips. The family wants to go to the Georgia Aquarium first.

“I just felt there’s got to be something I could do,” Moore said.

Two dinner seatings are planned for Thursday — 6 and 8 p.m.

On Tuesday, about 15 tickets were still available for both times, Moore said.

“We have been awed and overjoyed and humbled,” Lee said. “You never imagine you’d be in this position. You’re almost stupefied by people’s creativity, their energy, their effort.”

Reach Lauren Sausser at 937-5598.