Managing COVID Toes
One question I've been struggling with is, what do we tell these otherwise healthy patients with purple toes, especially those with no other symptoms? Many of them are testing SARS-CoV-2 negative, both with viral swabs and serologies. Some have suggestive histories like known COVID exposure, recent cough, or travel to high-risk areas. Do we tell them they're at risk of transmitting the virus? Should they self-quarantine, and for how long? Is there any consensus emerging?
This is a good opportunity to plug the American Academy of Dermatology's COVID-19 Registry, which is run by Esther Freeman at Massachusetts General Hospital. She has done a phenomenal job in helping us figure out the answers to these exact questions.
I'd encourage any clinicians who have a suspected COVID patient with a skin finding, whether or not infection is confirmed with testing, to enter information about that patient into the registry. That is the only way we will figure out evidence-based answers to a lot of the questions that we're talking about today.
Based on working with the registry, we know that, rarely, patients who develop pernio-like changes will do so before they get COVID symptoms or at the same time as more typical symptoms. Some patients with these findings are PCR positive, and it is therefore theoretically possible that you could be shedding virus while you're having the pernio toes. However, more commonly—and this is the experience of most of my colleagues and what we're seeing at UCSF—pernio is a later finding and most patients are no longer shedding the virus. It appears that pseudo-pernio is an immune reaction and most people are not actively infectious at that point.
The only way to know for sure is to send patients for both PCR testing and antibody testing. If the PCR is negative, the most likely interpretation is that the person is no longer shedding virus, though there can be some false negatives. Therefore, these patients do not need to isolate outside of what I call their COVID pod—family or roommates who have probably been with them the whole time. Any transmission likely would have already occurred.
I tell people who call me concerned about their toes that I do think they should be worked up for COVID. However, I reassure them that it is usually a good prognostic sign.
What is puzzling is that even in patients with pseudo-chilblains who have a clinical history consistent with COVID or exposure to a COVID-positive family member, antibody testing is often—in fact, most often—negative. There are many hypotheses as to why this is. Maybe the tests just aren't good. Maybe people with mild disease don't generate enough antibodies to be detected, Maybe we're testing at the wrong time. Those are all things that we're trying to figure out.
But currently, I tell patients that they do not need to strictly isolate. They should still practice social distancing, wear a mask, practice good hand hygiene, and do all of the careful things that we should all be doing. However, they can live within their home environment and be reassured that most likely they are in the convalescent stage.
I find the antibody issue both fascinating and confusing.
In my practice, we've noticed a range of symptoms associated with pseudo-pernio. Some people barely realize it's there and only called because they saw a headline in the news. Others complain of severe burning, throbbing, or itching that keeps them up at night and can sometimes last for weeks. Are there any treatments that seem to help?
We can start by saying, as you note, that a lot of patients don't need interventions. They want reassurance that their toes aren't going to fall off, that nothing terrible is going to happen to them, and often that's enough. So far, many patients have contacted us just because they heard about the link between what they were seeing on their feet and COVID. They were likely toward the end of any other symptoms they may have had. But moving forward, I think we're going to be seeing patients at the more active stage as the public is more aware of this finding.
Most of the time we can manage with clobetasol ointment and low-dose aspirin. I wouldn't give aspirin to a young child with a high fever, but otherwise I think aspirin is not harmful. A paper published in Mayo Clinic Proceedings in 2014, before COVID, by Drs Jonathan Cappel and David Wetter, provides a nice therapeutic algorithm. Assuming that the findings we are seeing now are inflammatory, then I think that algorithm should apply. Nifedipine 20-60 mg/day is an option. Hydroxychloroquine, a maximum of 5 mg/kg/day, is an option. I have used hydroxychloroquine most commonly, pre-COVID, in patients who have symptomatic pernio.
I also use pentoxifylline 400 mg three times a day, which has a slight anti-inflammatory effect, when I think a blood vessel is incidentally involved or the patient has a predisposition to clotting. Nicotinamide 500 mg three times a day can be used, though I have not used it.
However, during this post-COVID period, I have not come across many with pseudo-pernio who needed anything more than a topical steroid and some aspirin. But I do know of other physicians who have been taking care of patients with much more symptomatic disease.
That is a comprehensive list. You've mentioned some options that I've wondered about, especially pentoxifylline, which I have found to be very helpful for livedoid vasculopathy. I should note that these are all off-label uses.
Let's talk about some other suspected skin manifestations of COVID. A prospective nationwide study in Spain of 375 patients reported on a number of different skin manifestations of COVID.
You're part of a team doing critically important work with the American Academy of Dermatology COVID-19 Dermatology Registry. I know it's early going, but what are some of the other common skin presentations you're finding?
I'm glad you brought up that paper out of Spain. I think it is really good and does highlight the difference in acute versus convalescent cutaneous manifestations and prognosis. It confirms what we're seeing. Retiform purpura is an early finding associated with ill patients in the hospital. Pseudo pernio-like lesions tend to be later-stage and in younger, healthier patients.
Interestingly, the vesicular eruption that those investigators describe—monomorphic vesicles on the trunk and extremity—can occur in the more acute phase. That's fascinating to me because widespread vesicular eruptions are not a thing that we commonly see. If it is not an autoimmune blistering disease, and not a drug-induced blistering process, then you're really left with viral. Rickettsialpox can do that, as can primary varicella, disseminated herpes, disseminated zoster, and now COVID. So that's intriguing.
I got called to see a patient yesterday who had symptoms of COVID about a month ago. She was not PCR tested at the time but she is now negative. She has a widespread eruption of tiny vesicles on an erythematous base. An IgG for COVID is positive. How do we decide whether her skin lesions have active virus in them?
[Editor's note: An atlas with images of COVID-related rashes and other skin changes is available in the Wiley Online Library.]
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Cite this: Dermatologic Changes With COVID-19: What We Know and Don't Know - Medscape - May 13, 2020.