Nevocentric erythema multiforme after SARS-COV-2 vaccine.

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None.

Conflict of interest

None.

Data availability statement

Data sharing not applicable to this article as no datasets were generated or analysed during the current study

A 27‐year‐old woman presented to our Dermatology Unit referring an acute skin rash with no associated systemic symptoms. Three days before, the patient had taken the SARS‐COV‐2 vaccine (Comirnaty™ – BioNTech/Pfizer ‐ Mainz, Germany/New York, NY, USA). Physical examination showed erythematous, ring‐shaped plaques only surrounding several, but not all of her melanocytic nevi (Fig. 1a–d). Dermoscopy revealed typical melanocytic nevi having a reticular or globular pigment pattern, surrounded by a purpuric red ring (Fig. 2a,b). A clinical diagnosis of a nevocentric erythema multiforme (EM) was made. Therapy with cetirizine 10 mg and moisturizers was initiated with complete resolution seen after 2 weeks. At the follow‐up examination, no changes were found in her otherwise banal pre‐existing nevi.

Figure 1

Clinical images of nevocentric erythema multiforme presenting on arms (a and b), hands (c) and tights (d). Nevi of the back were not affected.

Figure 2

Clinical images showing the purpuric ring around the nevi. (a) Dermoscopically, a typical globular nevus is surrounded by a pinkish halo that becomes more prominent at the periphery (b).

Most cases of nevocentric EM reported in the literature were described as a postherpetic phenomenon. McKenna and Pariser reported two adult female patients with nevocentric EM affecting the trunk and limbs after a HSV infection of the lower lip. Monsálvez et al. described the case of a pregnant woman, with history of recurrent labial herpes, presenting with halos of erythema around her nevi. Finally, Di Brizzi et al. reported a case of a 9‐year‐old girl presenting a nevocentric EM after labial herpes. The only case non‐related to a herpetic infection was described by Humphreys and Cox occurring in a 37‐year‐old female patient after the ingestion of thiabendazone.

The reaction itself differs from the well‐known phenomenon described by Meyerson in 1971, which consists of an eczematous halo surrounding a pre‐existing melanocytic nevus, but it is not clear whether an interaction between CD4 T lymphocytes and increased expression of intercellular cell adhesion molecule 1 might be involved in both these nevocentric processes.

The course of nevocentric EM does not differ from the classical form of EM, and no alterations of the affected nevi were reported previously. Along these lines, patients can be reassured of the benign outcome of this condition.

Albeit the pathogenesis of EM ‘targeting’ nevi is obscure, in our case, we can hypothesize a similar mechanism as that involved in post‐HSV nevocentric EM. The specific vaccine used in our patient was a modified messenger RNA in lipidic nanoparticles that allows the liberation of a non‐replicant RNA inside the host cells, expressing the ‘S’ SARS‐COV‐2 antigen transitorily. It is therefore plausible that the vaccine may induce a similar reaction to that occurring after an HSV infection.

In conclusion, nevocentric EM is a benign, limited condition that can be added to the list of possible skin reactions associated with SARS‐COV‐2 vaccines.