Hypothetical Case of an Adult Presenting With Acral Lesions and COVID-19 Symptoms
A 50-year-old man presents with acute-onset, violaceous, painful, edematous plaques on the distal toes that began 3 days earlier and have progressed to include the soles. A review of symptoms reveals fever (temperature, 38.4 °C [101 °F]), cough, dyspnea, diarrhea, and severe asthenia. He has had interactions with a coworker who recently tested positive for COVID-19.
How Should You Consider These Lesions in the Context of the Other Symptoms Concerning for COVID-19?
In contrast to the asymptomatic child above, this adult has chilblainslike lesions and viral symptoms. In adults, chilblainslike lesions have been associated with relatively mild COVID-19, and patients with these lesions who are otherwise asymptomatic have largely tested negative for COVID-19 by PCR and serologic antibody testing.11,25,26
True acral ischemia, which is more severe and should be differentiated from chilblains, has been reported in critically ill patients.9 Additionally, studies have found that retiform purpura is the most common cutaneous finding in patients with severe COVID-19.27 For this patient, who has an examination consistent with progressive and severe chilblainslike lesions and suspicion for COVID-19 infection, it is important to observe and monitor these lesions, as clinical progression suggestive of acral ischemia or retiform purpura should be taken seriously and may indicate worsening of the underlying disease. Early intervention with anticoagulation might be considered, though there currently is no evidence of successful treatment.28
What Causes These Lesions in a Patient With COVID-19?
The underlying pathophysiology has been proposed to be a monocytic-macrophage–induced hyperinflammatory systemic state that damages the lungs, as well as the gastrointestinal, renal, and endothelial systems. The activation of the innate immune system triggers a cytokine storm that creates a hypercoagulable state that ultimately can manifest as superficial thromboses, leading to gangrene of the extremities. Additionally, interferon response and resulting hypercytokinemia may cause direct cytopathic damage to the endothelium of arterioles and capillaries, causing the development of papulovesicular lesions that resemble the chilblainslike lesions observed in children.29 In contrast to children, who typically have no or mild COVID-19 symptoms, adults may have a delayed interferon response, which has been proposed to allow for more severe manifestations of infection.12,30
How Should an Adult With Perniolike Lesions Be Managed?
Adults with chilblainslike lesions and no other signs or symptoms of COVID-19 infection do not necessarily need be tested for COVID-19, given the reports demonstrating most patients in this clinical situation will have negative PCRs and serologies for antibodies. However, there have been several reports of adults with acro-ischemic skin findings who also had severe COVID-19, with an observed incidence of 23% in intensive care unit patients with COVID-19.27,28,31,32 If there is suspicion of infection with COVID-19, it is advisable to first obtain workup for COVID-19 and other viruses that can cause acral lesions, including Epstein-Barr virus and parvovirus. Other pertinent laboratory tests may include D-dimer, fibrinogen, prothrombin time, activated partial thromboplastin time, antithrombin activity, platelet count, neutrophil count, procalcitonin, triglycerides, ferritin, C-reactive protein, and hemoglobin. For patients with evidence of worsening acro-ischemia, regular monitoring of these values up to several times per week can allow for initiation of vascular intervention, including angiontensin-converting enzyme inhibitors, statins, or antiplatelet drugs.32 The presence of antiphospholipid antibodies also has been associated with critically ill patients who develop digit ischemia as part of the sequelae of COVID-19 infection and therefore may act as an important marker for the potential to develop disseminated intravascular coagulation in this patient.33 Even if COVID-19 infection is not suspected, a thorough review of systems is important to look for an underlying connective tissue disease, such as systemic lupus erythematosus, which is associated with pernio. Associated symptoms may warrant workup with antinuclear antibodies and other appropriate autoimmune serologies.
If there is any doubt of the diagnosis, the patient is experiencing symptoms from the lesion, or the patient is experiencing other viral symptoms, it is appropriate to biopsy immediately to confirm the diagnosis. Prior studies have identified fibrin clots, angiocentric and eccrinotropic lymphocytic infiltrates, lymphocytic vasculopathy, and papillary dermal edema as the most common features in chilblainslike lesions during the COVID-19 pandemic.9
For COVID-19 testing, many studies have revealed adult patients with an acute hypercoagulable state testing positive by SARS-CoV-2 PCR. These same patients also experienced thromboembolic events shortly after testing positive for COVID-19, which suggests that patients with elevated D-dimer and fibrinogen likely will have a viral load that is sufficient to test positive for COVID-19.32,34-36 It is appropriate to test all patients with suspected COVID-19, especially adults who are more likely to experience adverse complications secondary to infection.
This patient experiencing COVID-19 symptoms with signs of acral ischemia is likely to test positive by PCR, and additional testing for serologic antibodies is unlikely to be clinically meaningful in this patient’s state. Furthermore, there is little evidence that serology is reliable because of the markedly high levels of both false-negative and false-positive results when using the available antibody testing kits.37 The latter evidence makes serology testing of little value for the general population, but particularly for patients with acute COVID-19.
Conclusion and Outstanding Questions
There is evidence suggesting an association between chilblainslike lesions and COVID-19.11,22,38,39 Children presenting with these lesions have an excellent prognosis and only need a workup or treatment if there are other symptoms, as the lesions self-resolve in the majority of reported cases.7-9 Adults presenting with these lesions and without symptoms likewise are unlikely to test positive for COVID-19, and the lesions typically resolve spontaneously or with first-line treatment. However, adults presenting with these lesions and COVID-19 symptoms should raise clinical concern for evolving skin manifestations of acro-ischemia. If the diagnosis is uncertain or systemic symptoms are concerning, biopsy, COVID-19 PCR, and other appropriate laboratory workup should be obtained.
There remains controversy and uncertainty over the relationship between these skin findings and SARS-CoV-2 infection, with clinical evidence to support both a direct relationship representing convalescent-phase cutaneous reaction as well as an indirect epiphenomenon. If there was a direct relationship, we would have expected to see a rise in the incidence of acral lesions proportionate to the rising caseload of COVID-19 after the reopening of many states in the summer of 2020. Similarly, because young adults represent the largest demographic of increasing cases and as some schools have remained open for in-person instruction during the current academic year, we also would have expected the incidence of chilblains-like lesions presenting to dermatologists and pediatricians to increase alongside these cases. Continued evaluation of emerging literature and ongoing efforts to understand the cause of this observed phenomenon will hopefully help us arrive at a future understanding of the pathophysiology of this puzzling skin manifestation.40