When Christian Campero visits the Boston Lawnmower Company on Route 9, "it's always nice to see him," General Manager David Kennedy says.

Monday afternoon, Campero, age 4-and-a-half, saw that four employees shaved their heads over the weekend.

They did it for him.

The Northborough pre-Kindergartener was diagnosed with T-Cell ALL Leukemia in August and has undergone chemotherapy "almost every day" at the UMass Memorial Medical Center in Worcester, starting the day after his diagnosis, his mother, Tricia Campero, said Monday. Christian will have chemotherapy for three-and-a-half years, and cranial radiation next year, she said.

The news soon reached Boston Lawnmower, where, Campero said she has worked for the same owner since age 15. She currently does Web design, graphic design and accounting.

“As soon as we were told that he’ll lose his hair, a lot of my family members said they’ll shave their heads," Campero said.

"And some guys around here don’t have any issue either. They said, ‘We’ll do it for Christian.’”

Kennedy said that "it was sad to hear what was going on, but he seems to be doing good now.”

“Anything we can do to support Christian, we’ll be happy to do it," Kennedy said.

Campero said T-Cell ALL Leukemia has "a very high cure rate," and that Christian "did reach remission after 15 days of treatment."

"They tell us he’s on the right side of this," she said.

The family first saw signs of the disease around Aug. 3, Campero said.

“My mother actually noticed that his lymph nodes were coming out of his neck," she said.

"So, we brought him to his pediatrician, who thought he might have strep or mono. And those tests kept coming back negative.”

Campero said she then asked for a blood test, “and when the blood test came back, it showed that he had leukemia.”

Campero said the news shocked her.

“It was not something we ever thought would impact our family,” she said.

“He was feeling fine. He only had a little fever, so we thought he was just getting a cold. But his tonsils were getting close together, too. He was snoring really loud.”

Christian now is in his third month of treatment, “which they started right away,” Campero said.

He has experienced a “very small amount of side effects,” she said. He gets tired. And he can't play contact sports.

“When they do gym class, he can’t really participate," Campero said.

Christian “started the school year, but then had to take about four weeks off,” she said.

“Today was his first day back. We kind of just have to see how it goes. It depends on how his immune system is and how he’s feeling," Campero said.

“We’ve been lucky, I’ve been told.”