COVID Toes: Dermatologic Observations and Theories
Observations and theories about the emergence of “COVID toes” in patients are discussed with Adam Friedman, MD, FAAD.
Fever. Cough. Difficulty breathing. These are the well-known symptoms of coronavirus disease 2019 (COVID-19). The Centers for Disease Control and Prevention has recently added more symptoms of the infection to its list, with new symptoms continuing to be reported. Curious among these emerging reports are what is being called “COVID toes” a unique presentation that concerns patients and perplexes doctors.
Although there are a number of skin manifestations associated with COVID-19, their significance is unclear, noted Adam Friedman, MD, FAAD. Urticaria is reported in patients with COVID-19 and “should not be surprising” as viral infections are a common cause of acute-onset hives. Dr Friedman is professor and interim chair of dermatology at George Washington School of Medicine and Health Sciences, Washington, DC. “In the hospital we are seeing acroischemia and necrosis associated with cytokine storm-induced [disseminated intravascular coagulation]”, he further stated. These events are only seen in severe cases and are markers for mortality.
As with any systemic viral infection, morbilliform eruption – or maculopapular eruption – is commonly seen in patients with COVID-19. As to the relationship between COVID-19 and skin presentations, Dr Friedman acknowledged that “Viral exanthems are bread and butter in dermatology.” The combination of immune response and viral molecular mimicry causes the classic morbilliform eruption. “That said, I think the way this virus invades our cells, via primed angiotensin-converting enzyme 2 (ACE2), and where ACE2 is expressed, it should not be surprising that we are seeing vascular reactions.”
However, “What is emerging as more than simply 1 or 2 case reports is what has been coined ‘COVID toes,’ a perniosis-like eruption on the feet,” he explained. The lesions have been reported as occurring on the toes and are characterized as tender reddish-purple pruritic papules and plaques that are accompanied by sudden substantial edema that can be uncomfortable. Although perniosis most often observed on the feet and hands as an abnormal response to cold temperatures, Dr Friedman noted that it is unclear if temperature plays a role its appearance in patients with COVID-19.
He explained that the toe presentation is likely a result of “endothelial vasculature injury likely owing to the inflammatory response to the virus entering the endothelium as well as due to the injury to ACE2, which is expressed by the endothelial cells, resulting in immune dysregulation.”
Although there may be an explanation for the appearance of COVID toe in patients, the toe manifestation does not seem to select a specific patient population, although Dr Friedman noted that it is often seen in younger patients. Based on its appearance in younger patients, Dr Friedman indicated that there is a suggestion that COVID toes may represent a good immune response to the virus, but there is not enough data yet to support the hypothesis. Moreover, Dr Friedman said that this phenomena is seen in febrile patients and those with the more common infection symptoms as well as asymptomatic patients. It is also not yet known if the presence of the toe manifestation can indicate the stage of infection or its severity.
What therapies are recommended for this symptom of COVID-19 infection? Although a protocol has yet to be established for COVID toes, treatment for perniosis typically involves warming of the affected area, topical steroids, and oral calcium channel blockers. Dr Friedman suggests a similar regime of warmth and a topical steroid to address the inflammation in the skin of patients with COVID-19. He also highlighted that in observation of patients with this complication, the symptoms often resolve without further treatment.
Physicians who have treated patients with COVID toes can enter their data in the Dermatology COVID-19 Registry, maintained by the American Academy of Dermatology. The physician and patient-sourced international registry aims to promote understanding of the dermatologic manifestations of COVID-19.s
Reference
COVID-19 Dermatology Registry. American Academy of Dermatology website. https://www.aad.org/member/practice/coronavirus/registry. Accessed May 7, 2020.
