If any of John and Suzanne Merrell's four daughters had to get cancer, the Columbia parents sometimes think, it's a good thing it was Amanda.

This is not to suggest that they would wish it on any child, or that the past year hasn't been full of dark moments that would test the resolve of any parent. It's just that there's something about Amanda.

"She's a fighter, this one," said John, 34.

When I met the Merrells last week at Children's Hospital -- John, Suzanne and daughters Courtney, 12, Emily, 7, Amanda, 3, and Samantha, 2 -- Amanda was wearing a sweat shirt that said, "Sugar & Spice." It reflects both sides of her personality. "Sugar: She's real sweet," said Suzanne, 36. "And spice: She's pretty spicy."

"It's like jalapeno pepper," said John.

In summer 2004, Amanda's parents noticed that the then-2-year-old's left leg was swollen. She also had a fever. An MRI revealed a matchbox-size tumor growing in her left shinbone. Over Fourth of July weekend, doctors diagnosed Ewing's sarcoma.

"It's one of the two most common bone tumors that we see in children," said Dr. Nita Seibel, a pediatric hematologist-oncologist at Children's Hospital. (The other is osteosarcoma.) "But the thing that's unusual in Amanda's case is she's pretty young to have it. . . . It's particularly associated with when children are undergoing growth spurts and is much more common in the teenage years."

Doctors aren't exactly sure what causes these tumors. Although they were once treated with radiation, researchers have discovered that that can lead to secondary tumors later in life. The standard treatment is a round of chemotherapy, then surgery and more chemotherapy.

Adults stricken by bone cancer often have only a part of their bone removed. It's replaced by a prosthetic bone implanted in the body. That doesn't really work with children, who, being children, are still growing. Amanda's leg would have to be removed.

I asked the doctor what would happen if Amanda's leg were not amputated.

"Then she would die," said Dr. Seibel. "The reason she would die is not because of the bone tumor itself as much as because these tumors can metastasize, and the areas they can go to are particularly the lungs and other bones."

Amanda's family prepared for her first six rounds of chemotherapy. The treatment went well, and Nov. 1, 2004, Dr. Robert Henshaw, an orthopedic oncologist at Washington Hospital Center, amputated Amanda's left leg at about the knee. He had told her parents: "This is to make sure she's cured and lives longer than all of us."

John and Suzanne hadn't gone into much detail about the operation with their daughter. Amanda knew there was something wrong with her leg, and, frankly, it sounds as if she was glad to see the aching appendage go. Her parents explained that her "leggy" was sick and she was getting a new one.

"She just lit up," said John. "She shouted, 'I'm getting a new leggy! I'm getting a new leggy!' "

It's a spirit Dr. Seibel has seen before. "If you told an adult he would lose a leg and go through all that, they would be depressed. . . . Children, particularly young children, they're sick, they deal with it and then they move on."

The round of chemotherapy after the surgery was harder on the toddler. It started well, said John, but "then she started bringing us handfuls of hair. That's when it really started coming home."

Amanda lost all her hair and then all her eyelashes -- all her eyelashes except for one, a tenacious lash that she called "Henry." Henry hung on, but eventually he succumbed, too.

Those were tough days. Hairless and gaunt, the 2-year-old reminded her father of Gollum from "The Lord of the Rings." Unlike Gollum, Amanda recovered. She was fitted for an artificial leg, but at first she preferred to use a tiny walker.

Then one day, a few weeks after she was home, Amanda pushed a button on a clock in the living room that played the song "It's a Small World."

She started rocking back and forth on her old leg and her new one. Amanda was dancing.

"We all basically broke down," said Suzanne.

Amanda walks fine now, with just the slightest hitch in her stride. The boys at her preschool think her "robot leg" is cool.

So does Amanda. It came with a skin-colored cover, but she prefers to leave it off. She likes seeing the green, yellow, red and blue of the leg's metal armature.

Amanda spent the summer in skirts and shorts, just another rambunctious, brown-haired 3-year-old. For Halloween, she was a princess.

"She knows she's different," said her mother. "But she doesn't act like it."

Helping Children

Amanda lost a leg, but she gained a life, a life that was given to her by Children's Hospital. You can help support the hospital and make sure that no child is turned away by making a tax-deductible donation to our annual campaign.

Our goal: $600,000.

Our total so far: $6,281.31.

There are three easy ways to donate:

Make a check or money order payable to "Children's Hospital" and mail it to Washington Post Campaign, P.O. Box 17390, Baltimore, Md. 21297-1390.

Go online to www.washingtonpost.com/childrenshospital and click on "Make a Donation."

To contribute by Visa or MasterCard by phone, call 202-334-5100 and follow the instructions on the recorded message.

To see photos of Amanda, go to www.washingtonpost.com/johnkelly.