A punch-biopsy was performed on the left second toe where the erythema was the most intense. It demonstrated classic findings for pernio: superficial and deep perivascular lymphocytic inflammation and papillary dermal edema on the acral surface.
Pernio, alternatively known as chilblains, is characterized by erythema, violaceous changes, and swelling at acral sites (especially the toes or fingers). There can also be blistering, pain/tenderness, and itch. Pernio results in an abnormal localized inflammatory response to nonfreezing cold and is more common in damp climates. Pernio may also occur in occupational settings where patients handle frozen food. When a patient presents with the classic findings and consistent history, biopsy is not strictly necessary, but can aid in a definitive diagnosis.
The pathogenesis of pernio is not clearly understood. Inflammation secondary to vasospasm and type I interferon immune response to repeated or chronic cold exposure likely play a significant role. Symptoms can arise within 24 hours of exposure and resolve just as quickly. However, persistent and repeated exposure can also trigger ongoing symptoms that last for weeks.
As with most autoinflammatory conditions, pernio has a proclivity to affect younger women. It also affects children and the elderly. Because it is an inflammatory response to nonfreezing cold temperatures, the disease tends to occur during autumn in patients who live in homes without central heating.
A diagnosis of idiopathic pernio necessitates excluding several other similar, cold-induced entities. These include acrocyanosis (due to erythromelalgia, anorexia, medications), Raynaud phenomenon, cryoglobulinemia, cold urticaria, and chilblain lupus (among others). Pernio tends to lack other clinical findings such as true retiform purpura.
Of note, during the COVID-19 pandemic, physicians identified a spike in the incidence of pernio-like acral eruptions. This phenomenon has been coined “COVID toes.” While the direct temporal and causal relationships between COVID-19 and the observed eruption has not been clearly established, any patient who presents with a new onset pernio-like eruption should receive a COVID-19 test to ensure proper precautions are followed.1
In our patient, the work-up did not show any evidence of other underlying conditions. As her symptoms were minimal, we provided reassurance and counseling on preventive measures such as keeping her hands and feet warm and dry. In cases where treatment is needed, high-potency topical corticosteroids can be utilized judiciously during flares to decrease local inflammation. (There is minimal concern for adverse effects due to the thicker skin on acral surfaces.) Another treatment option is oral nifedipine (20-60 mg/d). One double-blinded trial showed it can improve symptoms in up to 70% of patients.2
Clinical image courtesy of Jiasen Wang, MD; microscopy image courtesy of Shelly Stepenaskie, MD. Text courtesy of Jiasen Wang, MD, Aimee Smidt, MD, Shelly Stepenaskie, MD, Department of Dermatology, and Daniel Stulberg, MD, FAAFP, Department of Family and Community Medicine, University of New Mexico School of Medicine, Albuquerque.