Managing COVID toes
Dr. Lipper: 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?
Dr. Fox: This is a good opportunity to plug the American Academy of Dermatology’s COVID-19 Registry, which is run by Esther Freeman, MD, 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 given a workup 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.