key: cord-0914672-jukn888m
authors: Buján Bonino, Cecilia; Moreiras Arias, Noelia; López‐Pardo Rico, María; Pita da Veiga Seijo, Gabriela; Rosón López, Elena; Suárez Peñaranda, José Manuel; Sánchez‐Aguilar Rojas, Dolores
title: Atypical erythema multiforme related to BNT162b2 (Pfizer–BioNTech) COVID‐19 vaccine
date: 2021-09-02
journal: Int J Dermatol
DOI: 10.1111/ijd.15894
sha: cc575ff882a8caf5ab1b2e5ee12134907fdd80b8
doc_id: 914672
cord_uid: jukn888m

nan

The recently extended use of mRNA vaccines BNT162b2 (Pfizer-BioNTech) and mRNA-1273 (Moderna) due to the COVID-19 pandemic has allowed the description of multiple cutaneous adverse effects linked to this new type of immunization. Although erythema multiforme (EM) is a recognized rare adverse effect of many other vaccines, reports linking this reaction to mRNA ones are very scarce so far. We describe a case of atypical EM occurring shortly after the second dose of BNT162b2 with no other evident cause.

Erythema multiforme is an inflammatory skin condition classically linked to infections (herpes simplex virus and mycoplasma are the most common causes), but a wide array of triggers, including many other infectious agents, drugs, immunizations, and even internal diseases, have also been described. Hallmark lesions consist of predominantly acral, targetoid papules, made up of three concentric distinct zones. 1 However, clinical manifestations of EM are diverse, and it can present as atypical palpable lesions with an erythematous dusky body surrounded by a paler halo.

A 91-year-old woman presented with diffuse, erythematous, and pruriginous papules with a tendency to confluence into plaques, which started over her left deltoid area 6 days after receiving the second dose of BNT162b2 (Pfizer-BioNTech COVID-19 vaccine) injected in that location. The rash progressed over the following 10 days, involving her back, "V" of the neck, and extremities.

At the time of assessment, she presented large plaques in the injection site and in the central dorsolumbar area and buttocks, and also multiple papules on her extremities and trunk ( Fig. 1) . A discreet light pinkish erythematous border could be noted around some of the lesions. There were no signs of epidermal detachment. Mucosae were unaltered. She was afebrile and denied systemic symptoms except for mild asthenia. She also denied prodromal semiology or recent medication changes.

Two biopsies from the left deltoid plaque and a peripheral papule showed superficial dermal lymphocytic infiltrate obscuring the dermo-epidermal junction associated with hydropic changes and dyskeratosis of isolated or grouped keratinocytes not confined to the basal layer. Intraepidermal lymphocytes were also noted (Fig. 2) .

These findings, along with the clinical appearance of individual lesions, allowed the diagnosis of atypical EM to be made.

Due to the extent of the lesions, she was admitted for close surveillance and initial treatment with high potency topical corticosteroids (clobetasol propionate ointment). She did not develop complications, and the lesions gradually subsided, leaving residual hyperpigmentation. On the eighth day of admission, she was discharged owing to favorable evolution. It is also notable that this is the first COVID-19 vaccine-related EM having its onset after the second dose. Although their exact timing in the disease course is still not evident, an early recognition of these cutaneous manifestations would help in a prompt diagnosis and management of this new viral illness. 2 Hence, identifying asymptomatic COVID-19 patients with only skin findings is of great public health value. 3 To this extent, we report the case of a maculopapular exanthem 

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