A 55-year-old patient, followed for 3 years for localized plaque psoriasis, treated with dermocorticoids at the time of flare-ups, presented to the emergency room for a worsening of his psoriasis with the development of erythroderma. The clinical presentation occurred 10 days after a simple form of covid consisting of flu-like syndrome, myalgias, fever and cough. The patient was treated symptomatically with paracetamol and vitamin C, without recourse to synthetic anti-malarial drugs or oral corticosteroids. The general examination revealed a hemodynamically stable patient with a fever of 38°C. The dermatological examination revealed a dry erythroderma (Fig. 1). The patient was hospitalized for 2 weeks and a symptomatic treatment based on dermocorticoids was started at the beginning and then a specific treatment with anti-interleukin 12/23 (Ustekinumab) was started after a general assessment not contraindicating its use.

Figure 1.

Dry Erythroderma.

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The evolution was marked by a beginning of improvement from the first injection of ustekinumab and a skin whitening 2 months after the second one.

Erythrodermic psoriasis is a severe form of psoriasis. It may be a manifestation of unrecognized psoriasis or a complication of diagnosed psoriasis. Several factors have been implicated in the occurrence of this complication such as genetic mutation especially of CARD 14 gene,3 certain bacterial (streptococcal and staphylococcal) or viral (HIV, CMV and Epstein bar virus) infections4 and certain medications such us oral corticosteroids, synthetic antimalarials, beta-blockers, terbinafine, cyclins, and non-steroidal anti-inflammatory drugs.5 The occurrence of erythroderma in patients followed for psoriasis during covid-19 infection is a very rare event. To our knowledge, only two cases have been described in the literature. Ghalamkarpour1 was the first to report a case of psoriatic erythroderma 3 weeks after a mild form of covid-19 infection. In January 2022, Demiri2 reported a second case in a patient who presented with dry erythroderma 5 days after a moderate form of covid-19 infection. Several pathophysiological hypotheses may explain the link between covid-19 infection and the occurrence of this complication. Firstly, covid-19 infection is considered to be a stressful state for the body, leading to a decrease in immunity. However, stress alone cannot be considered as a directly responsible factor in the occurrence of posriasis erythroderma. Secondly, there is the aggravating influence of certain drugs used in the treatment of SARS-CoV-2 infection, in particular oral corticosteroids with a relapse effect and hydroxychloroquine, which is known to cause a dysregulation of epidermal transglutaminase, leading to keratinocyte hyperproliferation. A third hypothesis incriminates the SARS-CoV-2 virus as an aggravating factor in psoriasis thought the anti-viral immune response with increased production of pro-inflammatory cytokines such as interleukin 17, interleukin 23, interleukin 6, TNF alpha and INF alpha, the same being involved in the pathophysiology of psoriasis and especially the interferon gamma, implicated in the erythrodermic form.6 This hypothesis is supported by some published reports that have shown that psoriatic patients on biotherapies, such as anti-interleukin 17, developed fewer severe forms of covid-19 than those on topical therapy alone.7 There is also the role of Th2 type cytokines which are involved both in the anti-covid immune response8 and in the erythrodermic form of psoriasis.9 It also appears that, as it happens with streptococcus, the SARS-CoV-2 surface protein spicule behaves as a superantigen10, which would be supported by cases of exacerbation of psoriasis following Covid-19 vaccination.

In our patient, a coincidence cannot be formally eliminated but the hypothesis retained which would explain the appearance of this erythroderma is the infection by SARS-CoV-2, because of the temporal relation but also because he did not receive any of the treatments incriminated in the occurrence of this complication.

All authors contributed to the conduct of this work. All authors also state that they have read and approved the final version of the manuscript.

The authors did not receive any funding.

The authors have no conflicts of interest to declare.