Stumped by pediatric rashes? Emily A. Rose, MD, FACEP, FAAP, assistant professor of clinical emergency medicine at the Keck School of Medicine of the University of Southern California, Los Angeles County and USC Medical Center (Los Angeles) offered a rapid-fire session with plenty of visuals to help emergency physicians identify common rashes that can present in uncommon ways.

She compared the process of identifying rashes to reading an ECG saying “You must be a little systematic.” First, she recommends taking a thorough history. “Don’t forget to ask what have you been putting on the rash,” she said. “It can really change the look of a rash.”

Dr. Rose spent the rest of the session using photos to challenge the audience to “Guess the Rash.” First up was several variations of eczema, a common rash that can be bacterial, viral, or herpetic.

Photos of slapped cheek syndrome (also known as fifth disease or parvovirus B19) looked alarming, but the typically mild infection resolves by itself in a few weeks. According to Dr. Rose, most patients have no problem with this rash, but there are two populations you need to worry about: pregnant women and those suffering from sickle cell anemia.

After several slides showing various presentations, Dr. Rose suggested that the best way to identify roseola is by getting a good patient history. Reports of nasal sniffles and a generous fever of 102-104 degrees for one to two days is generally the tipoff. These patients often appear with mild symptoms.

Another rash that can look like roseola is measles. It starts on the head and neck, spreading down to the trunk. “Any time you have a rash, do a good head-to-toe exam,” Dr. Rose said. She will also often ask if the patient had recently visited Disneyland. “History gives it away,” she said.

Correctly identifying measles is important. “It’s a significant cause of both mortality and morbidity worldwide. It’s a public health issue and really important to diagnose,” she said.

The patient who presents with a headache prior to a rash may be suffering from chicken pox (also called varicella). But to correctly identify this rash, Dr. Rose recommends asking a few key questions. If it turns out that, two weeks previous, the patient had a play date with the “Vaccines are Evil” family, you probably have your answer.

Dr. Rose warned that a new strain of hand, foot, and mouth disease has emerged. “It’s hand, foot, and mouth on steroids,” she said. Called coxsackie enterovirus A6, it presents with “really impressive vesicles or in more extensive areas,” she said. Despite its appearance, she said that these children respond well to standard treatments.

Not all rashes require treatment but it is important to provide parents with a diagnosis. “Parents are disproportionally concerned about rashes,” she said. Whenever possible, reassure parents when a rash is self-limiting, but let them know that some rashes can go on for weeks.

When seeing any pruritic rash, consider scabies. The entire family will likely need to be treated with permethrin, ivermectin, or lindane. Although permethrin is a first-line treatment for scabies, Dr. Rose noted that there is a strain of permethrin-resistant scabies.

The biggest mimicker she sees is impetigo. “Consider this diagnosis any time you see a rash that’s spreading among kids,” she said. “I have seen many weird presentations of impetigo.”

One particularly dangerous rash is sepsis peritonitis necrotizing fasciitis, especially in a neonate losing his or her umbilical stump. The child will need IV antibiotics and admission to the hospital.

Any necrotizing fasciitis can be so sneaky, said Dr. Rose. Consider a diagnosis any time you see a rash with muscular-skeletal complaint, especially when the pain is out of proportion to the rash. “Although the LRINEC score is imperfect, use it,” she said.

Another tricky diagnosis is henoch schonlein purpura. “This is purely a clinical diagnosis,” she said. “There is no confirmatory lab tests. Gastrointestinal pain may be the only symptom.” Dr. Rose warned that these patients could easily develop renal disease. Steroids can decrease abdominal pain, but do not impact outcome.

Some rashes may be the result of infections or drug interactions. Stevens-Johnson syndrome is a medical emergency that requires hospitalization. More than 90 percent of the cases will involve two or more mucous membranes. If this syndrome is suspected, immediately discontinue all non-essential medications and provide wound care.

Kawasaki disease presents in two phases characterized by a fever lasting five days and rash. “Anytime you have a rash and fever, consider Kawasaki,” Dr. Rose said. The bad news is that there is now an atypical or incomplete Kawasaki disease that involves a fever that lasts less than five days. “Know that this exists,” she said. “Kids tend to get it as infants. They are the ones who have long-term complications, including cardiac complications. It’s important for us to make the diagnosis.”

Speaking about anaphylaxis, Dr. Rose said that 20 percent of the cases present without a rash. “Don’t waste your time with anything else—epinephrine is the treatment,” she said.

She concluded by encouraging physicians to consider the common causes of rashes first. “You are much more likely to see an atypical presentation of a common rash than a zebra,” she warned.