Puzzling pediatric diagnoses: Kawasaki disease linked with specific genetic polymorphism
October 1, 2008
Important pediatric diagnoses for consulting dermatologists include Kawasaki disease, an expert says. It recently has been linked with a specific genetic polymorphism, which suggests that uncontrolled inflammation plays a role in its etiology.
In particular, "Kawasaki disease is the most common cause of acquired heart disease in children," says Sheila Fallon-Friedlander, M.D., clinical professor, pediatrics and medicine, University of California San Diego Medical Center and Rady Children's Hospital, San Diego.
Diagnostic criteria for Kawasaki disease include fevers - usually high - lasting more than five days, plus any four of the following:
One telltale sign of Kawasaki disease is the characteristic groin rash that can appear early on, Dr. Fallon-Friedlander says. This is usually a confluent red rash that desquamates early on.
Physicians also must remember to look for conjunctivitis that's free of discharge and spares the limbal area around the iris.
"People have been trying to figure out for years what Kawasaki disease is," Dr. Fallon-Friedlander tells Dermatology Times.
Some evidence suggests it's related to Staphylococcus superantigens, coronavirus or a hyperactive IgA response, Dr. Fallon-Friedlander says.
More recently, "An association has been noted with a particular polymorphism in the ITPKC gene (Onouchi Y, Gunji T, Burns JC et al. Nat Genet. 2008 Jan;40(1):35-42.), which is involved with interleukin upregulation," she adds.
Patients who lack this gene are unable to control their inflammation response.
"Therefore," Dr. Fallon-Friedlander says, "we believe that Kawasaki disease stems from overly extensive, uncontrolled inflammation leading to vasculitis."
There might still be an infectious agent involved, she says, but the uncontrolled inflammation will occur only in susceptible children.
In February 2008, Dr. Fallon-Friedlander says, a flight from San Diego spread measles to Hawaii. It started with three unvaccinated San Diego children who had contracted the disease in Switzerland and, subsequently, infected local San Diego children, who then boarded a flight for Hawaii.
"With lower vaccination rates in certain areas, measles has become more of a problem," she says. "This is important because about one in 1,000 children who contract the disease can get encephalitis and other complications, such as diarrhea, pneumonia and acute otitis media."
Accordingly, she recommends identifying children who have rashes and fevers that might be consistent with measles and isolating them from the rest of one's practice.
Other symptoms include cough, coryza, Koplik's spots (first few days, buccal mucosae near molars) and exudative conjunctivitis.
Fortunately, most rashes are a less serious health issue, Dr. Fallon-Friedlander says. Other nonfatal rashes include those associated with Giannotti-Crosti syndrome, parvovirus and pityriasis rosea (PR).
"It's important to diagnose these rashes not because they are a major health risk to the patient, but rather because they can last a long time. They instill tremendous anxiety in patients and their families, and then the families start to 'doctor shop,'" she says.
Giannotti-Crosti syndrome - also called papular acrodermatitis - is characterized by monomorphous (often lichenoid) papules appearing mainly on the face, buttocks and extremities.
"What's unique about this rash is that it doesn't involve the trunk much," Dr. Fallon-Friedlander says. "The problem is that it can last up to a month and a half, so it's a concern for families. It helps them to know what it is."
In the United States, Giannotti-Crosti syndrome is most commonly associated with Epstein-Barr Virus (EBV), although in Europe, hepatitis appears more commonly in association with Giannotti-Crosti, she says.
Diagnostic tips for Giannotti-Crosti syndrome include feeling the liver and spleen and checking for lymphadenopathy, Dr. Fallon-Friedlander says.
"If the patient has an enlarged liver or spleen, we will check for hepatitis, because Giannotti-Crosti has been associated with hepatitis A and B. More often, though, patients will be infected with EBV," she adds.