October 2002

In June, a 6-year-old girl presented to the emergency department with a three-day history of a rash, a more recent sore throat and fever. The rash began on her legs, spreading upward, to include her face. She had previously been healthy and had no other complaints. There were no sick contacts. She is otherwise a normal, active child who mostly plays outside. Her immunizations are up to date.

On examination, her temperature was 102° F, with other vital signs being normal. There were multiple areas of linear lesions with some erythema, swelling and vesicles. Some were excoriated with areas of weeping, crusted “honeycombed” lesions, mostly on her legs and arms (figures 1-3). Her face was swollen with patchy erythema. Her throat appeared erythematous with exudate and with mild cervical adenopathy, and her rapid screen for group A streptococcus was positive. She also had a white blood cell count of 18,400 with 71% granulocytes and culture of one of the weeping skin lesions is pending.

What’s your diagnosis?

1. Impetigo
2. Contact dermatitis
3. Insect bites
4. Cellulitis
5. Both A & B

Answer

The answer is E, both impetigo and contact dermatitis. This problem of recognizing severe contact dermatitis and distinguishing it from cellulitis comes up every summer. I know we are just about out of the time of year when we see a lot of poison ivy, and similar types of allergic contact dermatitis, especially for those of you in the Northern parts of the country. But I just thought it bears revisiting before the next season rolls around, because invariably, some children are admitted to the hospital with presumed cellulitis that could be managed in the outpatient setting for this cellulitis look-alike.

We did not obtain photos of this patient’s face, but when poison ivy gets on the face of an allergic child, it can look fairly severe (figures 4-5), and often raises the concern of facial cellulitis, erysipelas, or orbital cellulitis. This will then get the child admitted to the hospital for intravenous antibiotics until the correct diagnosis is made. In the June 1998 issue of Infectious Diseases in Children, I presented a case of a child admitted with the presumed diagnosis of orbital cellulitis. Before the correct diagnosis was made, he had received IV antibiotics and a CT scan of the orbits and sinuses. I certainly understand the importance of aggressive management of such a potentially serious infection; however, with a good history that reveals some potential exposure to these plants (the Rhus genus of trees and shrubs), especially with a previous history of allergies, plus the characteristic linear lesions that can usually be seen, arrival at the diagnosis is easy. Rhus toxicodendron (poison ivy) is very common in our part of Texas and throughout the Southern states. History of exposure is just about any outdoor activity for children in the summer.

This patient’s course was also a bit complicated by the strep throat problem, and as it turned out, the culture of one of the weepy, impetiginous-like lesions on the skin grew group A strep as well as Staphylococcus aureus. So, it is likely that some of the crusty areas represented impetigo. Since severe contact dermatitis can have areas that appear essentially the same as impetigo (figure 6), but not necessarily be infected, appropriate therapy can be a little tricky. Many experts will recommend treating with an oral anti-staph antibiotic if there are such lesions, realizing it may well get better without it. In a case like this, where group A strep was found in the throat of a symptomatic child, the question of antibiotic therapy was easy. As noted, S. aureus was also recovered, and fortunately it was methicillin-sensitive. Many of our isolates from the community are now methicillin-resistant (MRSA), and these patients are returning with their skin and soft tissue infections getting worse.

If it is simple impetigo that you are dealing with, you could probably get by with just good topical therapy including soap and water and, perhaps, mupirocin (Bactroban, GlaxoSmithKline) twice a day. If oral therapy is indicated in a patient with an MRSA soft tissue infection, many experts recommend a combination of trimethoprim-sulfamethoxazole (TMP-SMX) and rifampin with fairly good results. Oral clindamycin may also be a good choice, but one needs to know if the MRSA is also resistant to erythromycin since cross-resistance can occur. One needs to also know that if a group A strep soft tissue infection is being treated, TMP-SMX does not work, but clindamycin will.

Quick improvement with steroids

Of course, poison ivy or any severe contact dermatitis can be treated with a short course of topical or oral steroids and topical soothing agents, such as wet dressings. The subsequent improvement often tends to be more rapid than one would expect with an infection like cellulitis or even impetigo. After a few days of therapy, this patient’s rash was markedly improved and by the end of a week, the lesions were well-healed (figures 7–9).

Insect bites are usually discrete lesions even when they become secondarily infected, as seen in figure 10, not resembling allergic contact dermatitis.

So the next time someone tries to admit a patient with cellulitis to your hospital, and it just doesn’t look right — too widespread and patchy, has streaks of erythema and/or vesicles mixed in, and there is a history of outdoor activity — think allergic contact dermatitis like poison ivy. You may save your patient unnecessary antibiotics, unneeded tests and days in the hospital. However, having said that, remember, don’t be cavalier with cellulitis, especially about the face and eyes. It could be life-threatening. Ain’t medicine fun?