such as lockdown conditions, which may be clarified with additional research.
Lindy P. Fox, MD, professor of dermatology at the University of California, San Francisco, who was not an author of either study, urged caution in interpreting these results. Data from the American Academy of Dermatology and a recent paper from the British Journal of Dermatology suggest a real association exists, at in least some patients. “It’s going to be true that most patients with toe lesions are PCR [polymerase chain reaction]-negative because it tends to be a late phenomenon when patients are no longer shedding virus,” Dr. Fox said in an interview.
Reports about chickenpox-like vesicles, urticaria, and other skin lesions in SARS-CoV-2 patients have circulated in the clinical literature and the media. Acute acro-ischemia has been cited as a potential sign of infection in adolescents and children.
One of the European studies, which was published in JAMA Dermatology, explored this association in 20 patients aged 1-18 years (mean age, 12.3 years), who presented with new-onset acral inflammatory lesions in their hands and feet at La Fe University Hospital, in Valencia, during the country’s peak quarantine period in April. Investigators conducted blood tests and reverse transcriptase–PCR (RT-PCR) for SARS-CoV-2, and six patients had skin biopsies.
Juncal Roca-Ginés, MD, of the department of dermatology, at the Hospital Universitario y Politécnico in La Fe, and coauthors, identified acral erythema in 6 (30%) of the cases, dactylitis in 4 (20%), purpuric maculopapules in 7 (35%), and a mixed pattern in 3 (15%). Serologic and viral testing yielded no positive results for SARS-CoV-2 or other viruses, and none of the patients exhibited COVID-19 symptoms such as fever, dry cough, sore throat, myalgia, or taste or smell disorders. In other findings, 45% of the patients had a history of vascular reactive disease of the hands, and 75% reported walking barefoot in their homes while staying at home. Only two patients reported taking medications.
In the six patients who had a biopsy, the findings were characteristic of chillblains, “confirming the clinical impression,” the authors wrote. Concluding that they could not show a relationship between acute acral skin changes and COVID-19, they noted that “other studies with improved microbiologic tests or molecular techniques aimed at demonstrating the presence of SARS-CoV-2 in the skin may help to clarify this problem.”
The other case series, which was also published in JAMA Dermatology and included 31 adults at a hospital in Brussels, who had recently developed chillblains, also looked for a connection between SARS-CoV-2 and chilblains, in April. Most of the participants were in their teens or 20s. Lesions had appeared on hands, feet, or on both extremities within 1-30 days of consultation, presenting as erythematous or purplish erythematous macules, occasionally with central vesicular or bullous lesions or necrotic areas. Patients reported pain, burning, and itching.
Skin biopsies were obtained in 22 patients and confirmed the diagnosis of chilblains; of the 15 with immunofluorescence analyses, 7 patients were found to have vasculitis of small-diameter vessels.
Of the 31 patients, 20 (64%) reported mild symptoms consistent with SARS-CoV-2, yet none of the RT-PCR or serologic test results showed signs of the virus in all 31 patients. “Because some patients had experienced chilblains for more than 15 days [under 30 days or less] at the time of inclusion, we can reasonably exclude the possibility that serologic testing was done too soon,” observed the authors. They also didn’t find eosinopenia, lymphopenia, and hyperferritinemia, which have been associated with COVID-19, they added.
Changes in lifestyle conditions during the pandemic may explain the appearance of these lesions, according to the authors of both studies, who mentioned that walking around in socks or bare feet and reduced physical activity could have indirectly led to the development of skin lesions.
It’s also possible that young people have less severe disease and a delayed reaction to the virus, Ignacio Torres-Navarro, MD, a dermatologist with La Fe University and the Spanish study’s corresponding author, said in an interview. Their feet may lack maturity in neurovascular regulation and/or the eccrine glands, which can happen in other diseases such as neutrophilic idiopathic eccrine hidradenitis. “In this context, perhaps there was an observational bias of the parents to the children when this manifestation was reported in the media. However, nothing has been demonstrated,” he said.
In an accompanying editor’s note, Claudia Hernandez, MD, of the departments of dermatology and pediatrics, Rush University Medical Center, Chicago, and Anna L. Bruckner, MD, of the departments of dermatology and pediatrics at the University of Colorado, Aurora, wrote that “it is still unclear whether a viral cytopathic process vs a viral reaction pattern or other mechanism is responsible for ‘COVID toes.’ ” Lack of confirmatory testing and reliance on indirect evidence of infection complicates this further, they noted, adding that “dermatologists must be aware of the protean cutaneous findings that are possibly associated with COVID-19, even if our understanding of their origins remains incomplete.”
In an interview, Dr. Fox, a member of the AAD’s’s COVID-19 Registry task force, offered other possible reasons for the negative antibody tests in the studies. The assay might not have been testing the correct antigen, or the timing of the test might not have been optimal. “More studies will help this become less controversial,” she said.
The authors of the two case series acknowledged potential limitations of their studies. Neither was large in scope: Both took place over a week’s time and included small cohorts. The Belgian study had no control group or long-term follow-up. Little is still known about the clinical manifestations and detection methods for SARS-CoV-2, noted the authors of the Spanish study.
The Spanish study received funding La Fe University Hospital’s department of dermatology, and the authors had no disclosures. The Belgian study received support from the Fondation Saint-Luc, which provided academic funding for its lead author, Marie Baeck, MD, PhD. Another author of this study received personal fees from the Fondation Saint-Luc and personal fees and nonfinancial support from Bioderma. The authors of the editor’s note had no disclosures.
SOURCES: Roca-Ginés J et al. JAMA Dermatol. 2020 Jun 25. doi: 10.1001/jamadermatol.2020.2340; Herman A et al. JAMA Dermatol. 2020 Jun 25. doi: 10.1001/jamadermatol.2020.2368.