With her family’s encouragement, this 17-year-old girl self-refers to dermatology for a recurrent facial lesion. It has reappeared in the same location and in the same manner over the past 18 months; they suspect it is a staph infection.
First, the patient experiences localized itching and tingling in the same location on her left upper eyelid. Within a day or two, clusters of tiny blisters appear and the surrounding skin becomes erythematous. Ten days or so into the episode, the blisters begin to scab over and the redness subsides. Within two weeks, the condition totally resolves, only to reappear later.
Each time, she has been seen in an urgent care clinic, given a diagnosis of staph infection, and prescribed a 10-day course of trimethoprim/sulfa, which appears to clear the infection.
This case nicely illustrates the curious nature of extragenital/extralabial herpes simplex virus (HSV), which can manifest in virtually any location on the body. We can all agree that HSV far more commonly affects the lip, where a lesion such as this one would be readily recognized. But the diagnosis becomes problematic when the same blisters appear in an unfamiliar location.
Assumptions are made, often fueled by family fears, themselves fed by opinions from other well-meaning friends and acquaintances. And in such cases, treatment with antibiotics certainly appears to corroborate the diagnosis because it “works.” But the family’s nagging question of “Why?” is reasonable, and the answer telling.
The truth is, it would be quite out of the ordinary for a staph infection to present with grouped vesicles on an erythematous base, over and over again in the same location. It would also be unlike staph to merely tingle and itch, since pain and tenderness are far more typical.
If we really wanted to rule out staph infection, we would have to obtain a culture, which would not only provide an organism but also solid information about which antibiotics are likely to be effective against that particular organism. Had that been done in this case, the culture would have shown “no growth,” leaving us where we started, since a routine culture only identifies bacteria. A viral culture, taken from the vesicular fluid, would probably have proven the culprit to be herpes—but that possibility would first have to be entertained.
Had herpes been considered as a diagnosis, other corroboratory historical facts might have included the patient’s history of severe atopy, plus the fact that most of the episodes occurred during periods of increased stress. Both of these factors are well known to predispose patients to a number of skin infections—most notably, HSV. The premonitory symptoms of tingle and itch (and sometimes a bit of pain) were also instructive.
It also helps simply to know that such HSV infections are quite common (though often, as in this case, misdiagnosed). I’ve seen HSV in the scalp, on the ear, on the chest, on fingers, toes, thighs, and on the bottom of the foot. I’ve also seen it affect the eye itself, where it can cause scarring of the cornea. Fortunately, our patient had no symptoms referable to the eye. Had that been the case, referral to ophthalmology on an urgent basis would have been necessary.
Had this condition occurred only once, other items in the differential might have been considered: contact dermatitis and the blistering diseases (pemphigus, bullous pemphigoid, and others). But the recurrent nature was all but pathognomic.
For this patient, there was no effective treatment for the current episode, since the acyclovir family of antivirals can only slow viral replication, which had already taken place. But I did provide a prescription for valcyclovir 500-mg capsules, dispensing 10. The patient was advised to take them twice a day for five days, starting at the earliest signs of her next episode, which should halt the progression. If the patient has more than six or eight eruptions a year, a case could be made for prophylactic medication to be taken daily.
Ultimately, the most valuable thing provided to this patient was the answer to the questions: What is this, and why does it affect me? Two good questions remain unanswered: How did she get HSV in that exact location? And how can we cure her? With a little luck, in the reader’s career, we’ll come up with a cure, just as science came up with the acyclovir family of medicines early in my career.
• Grouped vesicles on an erythematous base, recurring in the same location, are HSV until proven otherwise.
• HSV episodes typically last 10 to 14 days.
• Staph infections are typically painful, and rarely recur in the same locations.
• Atopy predisposes to extralabial HSV.
• There are many causes of inflammation, only one of which is infection.
• There are many types of infection that are not bacterial (eg, viral, fungal, protozoan).