Despite Herculean advances in medical science, some children have diseases or disorders that are so rare or confounding that a diagnosis remains elusive. Here is one boy’s story.

Eight-year-old Evan has donned his hockey skates — and his game face.

He’s fully padded and loaded for bear, and there is nowhere he’d rather be.

Time to execute a practice drill called the “Superman,” where all the kids run and dive on the ice.

But while Evan’s enthusiasm is high, his form is a little different from the other boys. When he starts to dive, his legs don’t extend fully. When the other boys pop up off the ice with little effort, Evan has to struggle to pull himself up.

And while other kids may be energized by their physical activity, it will leave Evan entirely depleted.

For Evan’s mom, Jessica, to see her son participate at all is a small miracle.

“He travels a wonky medical path,” Jessica says.

Since he was a toddler, Evan has struggled with a host of medical challenges — from persistent pain in his limbs to extreme fatigue that keeps him out of school to serious infections that have put him in the hospital.

Evan is among a small percentage of children for whom, despite a range of neurological and genetic testing and examination, an overall diagnosis remains elusive.

“Evan has a bunch of minor diagnoses,” Jessica says. “He has dysautonomia, he has acute allergies and asthma, he has a mitochondrial disorder. But there’s no ‘big picture’ answer yet. It’s all believed to be secondary to the big ‘unknown.’”

Melissa Crenshaw, M.D., is medical director of the Clinical Genetics program at Johns Hopkins All Children’s Hospital. She says with so many advances in testing in recent years, many families are finding answers they seek. But there is still a percentage of children for whom there is no immediate diagnosis that fits.

“I tell families that what we’re learning about DNA is always changing,” Crenshaw says. “So even if we don’t find an immediate answer, consider it a work in progress. That is our commitment to these families, because we want to find answers as much as they do.”

What doesn’t change for patients who have complex illnesses is the need for a range of clinical specialties staffed with highly skilled experts. A patient may have needs in the areas of cardiology, physiatry, neurology, neuropsychology, pulmonology, gastroenterology, rheumatology and other specialties to treat symptoms that manifest and to help monitor for future problems.

Jessica says even as they live out this medical mystery, certain specialists at Johns Hopkins All Children’s have made a world of difference for her child, including Juan Dumois, M.D., a pediatric infectious diseases physician.

“Dr. Dumois has literally changed my kid’s life, and I don’t say that lightly,” Jessica says. “He’s left no stone unturned. He’s helped us manage Evan’s symptoms as they come up, and helped us stay on track to finding answers.”

Even the most adept and experienced physicians may feel as much like detectives as doctors at times.

“About half the patients I see in clinic are lacking an explanation for their problem,” Dumois says. “Sometimes a diagnosis is obvious, but other times it’s more nebulous.”

Dumois is able to research, to collect clues and draw out information that a child’s pediatrician may not have time or resources to do.

“After recommending a management plan, I’ll carefully follow the patient over time to see if a diagnosis pans out or if we need to continue our search.”

Having a diagnosis for this population of patients wouldn’t necessarily change the treatment plan for some. James Chinarian, M.D., is a pediatric rehabilitation medicine specialist at Johns Hopkins All Children’s. He says these children often still need physical, occupational and speech therapies, with or without a diagnosis in hand.

“I hope that gives families peace of mind that, regardless, our goal is to give children every opportunity to improve, to foster better mobility, to help their speech and language skills, and to maximize their independence.”

Still, a diagnosis can help light the path for a family navigating a complex medical journey. And sometimes, there can be a solution in the form of new medications or enzyme or gene therapies that can make a difference in the life of a child.

“I would give anything in the world for a diagnosis,” Jessica says.

To that end, she will continue the collaboration with the team of physicians and specialists she has come to trust and admire.

They’ll work together to keep her child as well as he can be and fully engaged in the arena of life — hockey skates and all.