April 2006

An 8-month-old male infant was referred for admission to the hospital with the diagnosis of varicella and pneumonia. The history of the illness began five days earlier with the onset of some discomfort in the inguinal area. He then had the onset of intermittent fever to 104°F and a rash in the diaper area about three days later. His past medical history was unremarkable, and his immunizations were up-to-date. There were no known sick contacts, but he did attend day care. However, varicella had not been reported at the day care center. Upon arrival, the patient was placed on airborne precautions in a private room with negative airflow.

Examination upon admission revealed normal vital signs, with a temperature of 97°F. The rash, shown in figures 1-3, contained discrete vesicular lesions, blisters and denuded areas consistent with larger blisters having previously ruptured, and were completely confined to the diaper area. The rest of his exam was normal, including his lungs. His chest radiograph, however, did reveal a right middle lobe density as shown in figure 4.

Laboratory tests performed included a complete blood count (CBC) with a white blood cell (WBC) count of 24,300, with 47% segmented neutrophils, 31% lymphocytes and 20% monocytes. Blood culture is pending. Rapid influenza and respiratory syncytial virus (RSV) tests were both negative. Vesicular fluid was sent for herpes simplex virus (HSV) and varicella virus polymerase chain reaction(PCR) and standard bacterial culture. Gram’s stain was not obtained. Treatment was begun with IV acyclovir and clindamycin.

What’s Your Diagnosis?
Pneumonia, plus:

1. Pityriasis lichenoides et varioliformis acuta (PLEVA)
2. Bullous impetigo
3. Bullous varicella
4. Candida diaper dermatitis

Answer

The next morning, the child was diagnosed with bullous impetigo (B) with coincident, subclinical pneumonia and the child was discharged home on oral clindamycin. He had no more fevers and was well at follow-up 48 hours later. The only positive test from the microbiology lab was the bacterial culture of a lesion, growing Staphylococcus aureus, resistant only to penicillin and ampicillin. These skin infections are usually caused by a phage group 2 S. aureus that produces a low molecular weight protein that causes the lysis of cells in the granular layer of the epidermis. This epidermolytic toxin-producing staphylococcus can be recovered from the blister fluid of the individual lesion, whereas in staphylococcal scalded skin syndrome the toxin is circulating, with a deeper Staphylococcus focus elsewhere, like an infected wound, etc. Treatment, of course, is usually a systemic anti-staph antibiotic. But, it’s very important to get a culture of the source in order to confirm the cause and sensitivities.

PLEVA is an acronym for “Pityriasis lichenoides et varioliformis acuta.” This is a very uncommon dermatological condition of school-aged children. It’s not an infectious disease at all. However, I have seen several cases, and each one was referred for evaluation of “atypical varicella”. It starts with the eruption of maculopapular lesions that occur in crops in a generalized distribution, much like varicella, and progresses to a crusting stage (figure 5). There is no fever or other associated findings. One of the key differentiating features is a lack of vesicles, like one sees in varicella. The cause is unknown, and the duration may be many months, but ultimately it is self-limiting, requiring no treatment.

Bullous varicella was not uncommon when varicella was commonly seen (figure 6). It is, of course, varicella lesions individually infected with the same staph that causes bullous impetigo noted above. It generally responds well to oral anti-staph antibiotics and hygiene. As I have mentioned in several previous columns, empiric therapy should nowadays be effective for methicillin-resistant S. aureus. My choice is oral clindamycin at about 30 mg/kg/day in three divided doses. I also always recommend obtaining a culture from one of the lesions. If it turns out to be a methicillin-sensitive strain S. aureus (MSSA), then an anti-staph penicillin would be the drug of choice. However, from a practical standpoint, getting a child to take oral dicloxacillin suspension is very difficult due to the taste. I learned this the hard way 26 years ago when I tried to get my daughter to take it. It turned this pleasant, normally very cooperative 6-year-old girl into the kid seen in The Exorcist. So I tasted it myself and learned a valuable lesson. I know with proper counseling of the parents and persistence, it can be done, but most people just don’t want to do it. I’ve found that oral cephalexin is a reasonable choice for these young children with MSSA infections. Once they can take capsules, then I use dicloxacillin. The other issue with this case is the diagnosis of varicella in the first place. I have never seen or heard of a varicella rash confined to the diaper area. If you have, please let me know so we can all be enlightened in the next issue.

Diaper rashes are frequently secondarily infected with Candida albicans, often producing a bright red rash with satellite lesions (figure 7). Although they may also have some pustular lesions, it’s not likely to appear bullous or blistering.

Commentary

I hope to see you at the 26th Annual (and last) National Pediatric Infectious Diseases Seminar in San Francisco this month. Lastly, the 29th of next month is Memorial Day. Please take that opportunity to remember and honor our military, especially keeping in mind our fellow physicians and surgeons who are deployed. Be safe and please keep in touch at jhbrien@aol.com.