An ongoing dialogue on HIV/AIDS, infectious diseases,
December 30th, 2014
Common Curbsides: The Patient with “Recurrent Zoster”
Just in time for the New Year celebration, here’s a curbside consult I’ve received several times, probably because the answer isn’t in most textbooks. As usual, the actual question is slightly edited, as well as lightly (and affectionately) annotated:
Hey Paul [I like that casual salutation] — Quick question [of course] — I have a patient with a history of irritable bowel, otherwise well, who had shingles on her lower back a few years ago, approximately L5-S1 [love those dermatome maps]. It was pretty bad, but ultimately improved on Valtrex. Since then she’s contacted me several times with recurrent zoster in the same distribution, each time it improves with more Valtrex. She’s not immunocompromised, HIV negative, not on steroids, etc.
Should she be on chronic suppressive treatment? If so, what drug and what dose? And how long should she be on it? Any role for the shingles vaccine? [Hey — you said “Quick question” — not “questions”! That will cost you.] She’s only 42. [Agree with the “only 42”; that’s very young, at least compared to some ID specialists who have blogs.]
Gracias! [Espanol! Excelente!],
Juanita [not her real name, but it matches with the Spanish expression of gratitude]
There’s a reason doctors have questions about their patients with frequently recurring zoster — it’s because the entity doesn’t really exist. That makes finding guidance for management extremely difficult!
Recurrent zoster is rare enough that some question whether it makes sense to give the vaccine to people with a history of shingles, though in my experience these are understandably the patients with the greatest motivation to get vaccinated, so I’m glad the guidelines do endorse this practice. And one population-based study did find that a single recurrences of zoster occurred in people with a history of shingles at about the same rate as an initial episode. Prolonged pain was a risk factor for having another episode.
So if it isn’t recurrent zoster most of these patients are experiencing, what is it? So far all of the cases I’ve been referred have been one of these three things:
- Herpes simplex. This is far and away the most common mimicker. Obviously the skin lesions can look a whole lot like zoster, and since HSV is usually found in the oral or anogenital areas, the clinician and patient just don’t think about it when clusters of vesicles crop up somewhere else. (It’s what our very young patient summarized above had, of course.) Establishing the diagnosis is usually straightforward, either through a careful history or viral culture/DFA of an active lesion. Warning — some people with a history of “recurrent zoster” aren’t too thrilled to hear they have herpes instead, especially of the Type 2 variety, so caution when informing him/her of this diagnosis. All kinds of relationship turmoil can ensue.
- Post-herpetic neuralgia complicated by “neurodermatitis.” I put that last word in quotes, because that really isn’t the most common use of the term, but it truly fits. Here’s what happens — the patient with zoster has, as a manifestation of post-herpetic neuralgia, tingling and itching at the site. He/She then scratches and picks at it relentlessly, until the skin is red and bumpy — which is then mistaken for “recurrent zoster.” These itchy red bumps really look nothing like shingles, and of course are associated with no viral replication, but the location right at the site of prior shingles fools people.
- Wolf’s isotopic response. I’m lucky to have a brilliant dermatologist as a colleague; he clued me in to this oddly named entity, which is a fancy way of saying “a new skin disease at the site of an already healed, unrelated disease.” Turns out herpes zoster is the most common initial skin lesion, and then a whole host of other things can occur in that same site. Despite the name, it has nothing whatsoever to do with radioactivity, but sure will impress your friends if you mention it in casual conversation.
I’m sure this short list isn’t comprehensive, but you get the point. If you and the patient think it’s recurrent zoster happening over and over again, it almost certainly is something else, and the three entities listed above are a good place to start.