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Skin necrosis after COVID‐19 vaccines

COVID-19 is associated with a wide variety of skin manifestations. Some of them have also been observed as reactions to COVID-19 vaccines. Severe vaccine-related skin reactions are unusual, but they can be potentially hazardous and require systemic medication [1, 2]. Here, we describe the first case of skin necrosis following Moderna vaccine. We also review previous cases of skin necrosis after other COVID-19 vaccines to characterize this entity. A 22-year-old man presented with severe pain and darkening of the skin on his feet. He had received his first dose of the Moderna vaccine five hours before the onset of symptoms. Physical examination (Figure 1a) revealed a large 4 cm necrotic plaque on the right hallux. Smaller purpuric macules were found on the dorsum of both feet. Dorsal pedal, posterior tibial, femoral and popliteal pulses were present and symmetrical. Mobility and sensation were conserved. Laboratory results were unremarkable, including blood count, coagulation, autoimmunity, serology, and a thrombophilia screen. Doppler ultrasound showed preserved flow with normal velocity. Transthoracic echocardiography ruled out the presence of endocarditis. Fundoscopy and optical coherence tomography (OCT) were unaltered. Skin biopsy revealed focal epidermal necrosis, a superficial perivascular lymphohistiocytic infiltrate with isolated eosinophils in the dermis, and signs of thrombotic vasculopathy. Based on the above, the diagnosis of skin necrosis as an adverse reaction to the Moderna vaccine was established. The patient started treatment with acetylsalicylic acid 100 mg/day and oral prednisone 30 mg/day on a tapering schedule, with a rapid stabilization of the lesions. Medication was discontinued after one month due to the good evolution of the necrosis, with partial re-epithelialization. Complete healing took two months (Figure 1b). The second dose of the Moderna vaccine was suspended as a precautionary measure. Since the start of mass vaccination campaigns against COVID-19, several skin reactions have been notified. Most of them are mild to moderate and respond to one of the following six clinical patterns: COVID-arm, urticaria and/ or angioedema, morbilliform, maculopapular, papulovesicular, pityriasis rosea-like and purpuric rashes [1, 2]. Skin thrombosis and necrosis are very rare, with only three cases Clinical Letter