Everyone has heard the term “textbook cases”. In recent weeks, RiverWalk allergist Bryan Stone, MD has had three such cases jump right off the page and into his office.

Last year, preparing for his allergist board recertification, Dr. Stone decided to study unusual syndromes that he’d heard and read about.

“I had a feeling these might come up on the test,” he says.

Sure enough, he encountered these topics when he took – and passed – the exam.

Flash forward a year later: his study has paid off in real terms. Within a two-week span, Dr. Stone has seen and resolved cases of some of the same rare conditions he boned up on for the exam.

The first case was referred by a non-Pentucket primary care practice. The patient was having what seemed to be anaphylactic reactions with no obvious cause. She’d seen multiple physicians who hadn’t been able to diagnose her problem. Meanwhile, she was suffering.

“She’d been using her EpiPen about five times a week,” says Dr. Stone, “each time going to the emergency room thinking she was having a severe allergic reaction.”

“I had a hunch,” he says, “and sent blood samples to our lab for a baseline tryptase test. The first result was mildly positive, but a second test turned out to be strongly positive.”

The patient, diagnosed by Dr. Stone as having mast cell activation syndrome, is now back in the care of her PCP, who is referring her to a hematologist. Things are looking up for her.

“[Mast cell activation syndrome is] not an allergy, but it masquerades as one. It’s really a cellular disorder at the genetic level,” Dr. Stone states.

While this was going on, another patient presented with ailments that mimicked allergic reaction. Again, there seemed no obvious cause. But it rang a bell that hearkened back to last year’s board exam.

Cases of hereditary angioedemas are rare – about one in 50,000 individuals. They are also dangerous: swelling around the eyes, lips, hands and feet that can be life-threatening, when restricted airways cause the patient to choke. The disease is known to be difficult to diagnose, but by process of elimination, indicators were pointing in that direction.

“All the lab tests for the better researched hereditary angiodemas came back negative, so I suspected it was Type 3,” says Dr. Stone. “There is no FDA-approved test for this problem. Diagnosis has to be made clinically. I consulted with a friend at Harvard Medical School who had seen a couple of dozen of these cases. He agreed and felt this was the only thing it could be.”

The patient was prescribed a new type of medication and after two weeks was clear of symptoms.

“So far it (the prescription) is working like a charm,” Dr. Stone says. “Which is also proof that we made the right diagnosis.”

Just a few weeks ago, yet another unusual case came in, a patient that Dr. Stone diagnosed as having urticarial vasculitis.

“It looks like hives,” he says, “but it’s not due to allergy, but to an inflammation of the blood vessels. The hives last longer and they leave dark patches. It’s an important diagnosis to make because it only responds to specific medications that are never prescribed for garden-variety hives.”

Three diagnoses of unusual cases in as many weeks has left Dr. Stone a bit bemused.

“You never know what’s going to come in on a given day,” he says. “And that’s what makes practicing medicine fun. For these cases that had shown up on my board exam to actually walk through the door at RiverWalk, that is pretty remarkable.”