Itchy skin: Imaginary bugs often blamed

People with a "delusional bug syndrome" are convinced that bugs, worms, germs, or other creepy crawlers are infesting their skin and often see skin doctor after skin doctor to find out what is causing the infestation. Often, patients bring in samples of the insect and request a skin biopsy.

But new research published online in the Archives of Dermatology finds that in the case of delusional skin infestation, neither samples nor biopsies show any evidence of skin infestation.

Researchers at Mayo Clinic in Rochester, Minn., reviewed 108 people with symptoms resembling delusions of parasitosis (infection with a parasite). Some of the patients brought samples, others had biopsies of their skin, and some had both.

"When we looked at what they brought in and when we looked under the microscope, we never found a parasite," says study author Mark Davis, MD, a professor of dermatology at the Mayo Clinic.

Of 80 self-procured specimens, 10 were insects, but nine of them were not capable of infestation. One person brought in a sample of pubic lice, which is technically capable of infestation, but not the type that could cause head-to-toe itching. The other specimens were dead skin, plant material, or environmental debris.

Slightly more than 60% of these patients were diagnosed with dermatitis, which is characterized by inflamed, itchy skin, the study showed.

There are no exact numbers on how many people have delusional skin infestation, but it is "relatively frequent," Davis says.

Invisible bug syndrome is psychiatric illness

This is a psychiatric condition, but people with a "delusional bug syndrome" typically see a dermatologist.

"The patient refuses to believe it is a psychiatric disorder because they have a false, fixed belief, so even if you present them all of the evidence, they still believe they have parasites invading their skin," Davis says. "They travel from center to center for another opinion because they really believe their skin is infected."

It is a devastating illness, he says.

"They are very upset because they believe their skin is infested with all sorts of nasty things and we don't see anything or find anything with a biopsy and yet they are in our office, their lives are ruined, and they want treatment," Davis says. "Patients say 'you are just missing it and not looking carefully enough,' and just walk out."

Dermatologists' dilemma

This condition is the bane of many dermatologists' existence, says Bruce Strober, MD, an assistant professor of dermatology at New York University Langone Medical Center in New York City. "People with delusions of parasitosis are a great challenge to us," he says. "It's clearly a psychiatric disorder that requires psychiatric medication and counseling. Unfortunately, these patients are rarely amenable to those approaches."

Donald S. Waldorf, a dermatologist in Nanuet, N.Y., has seen his fair share of patients with a delusional bug syndrome. As a result, he has developed his own approach to treating these patients.

"They often come in with a bag of stuff, including threads and dead skin, but nothing real and capable of infestation," he says. "They also dig at and scratch their skin."

Waldorf will often prescribe topical agents to prevent infections from scratching and may suggest steroids to reduce inflammation. Sometimes, he will prescribe psychiatric medications.

"They won't go to a psychiatrist," he says. "If tell them to go, I will have lost them, so I basically give them support and prevent infection," he says.