Pityriasis lichenoides et varioliformis acuta after SARS-CoV-2 infection and relapse after vaccination.

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A 21‐year‐old, otherwise healthy, woman presented in emergency with a 4‐week history of a widespread eruption. She had no past history of skin diseases, and her only medication was birth control pills. In early July, she had presented fever for 2 days and cough for 5 days. She was subsequently found a positive nasopharyngeal swab for SARS‐CoV‐2. She also reported sore throat 1–2 weeks after COVID‐19 infection. She had not received COVID‐19 vaccination. At the end of July, 2–3 weeks after COVID‐19 infection, a rash started on the abdomen and spread widely from scalp to the lower limbs. Upon referral at the end of August, she presented with an itchy and painful eruption of monomorphous dark red papules. The skin lesions represented different stages, ranging from recent active papules to crusts and hypopigmented scars. They were distributed widely on the trunk, abdomen, back with a ‘Christmas tree’ pattern (Fig. 1a), upper arms, tights and legs (Fig. 1b). All mucosae were spared. The patient was in good general health with no systemic symptoms. A skin biopsy of a recent lesion revealed focal necrosis of the epidermis, parakeratosis, lymphocytic exocytosis and an inflammatory infiltrate of lymphocytes, macrophages and neutrophils as well as extravasation of red blood cells were found in the upper dermis (Fig. 2). The clinical presentation and histological findings were consistent with pityriasis lichenoides et varioliformis acuta (PLEVA). Laboratory findings (complete blood count, C‐reactive protein) were unremarkable; and serology for any other possible triggering infection (EBV, CMV, toxoplasmosis, parvovirus B19, HIV, hepatitis B and C) was negative. The patient was hospitalized for a week and was given a course of oral prednisolone (40 mg/daily, 0.7 mg/kg/day) with topical betamethasone dipropionate 0.1% ointment. Because of a lack of response after 1 week of treatment, narrowband UVB phototherapy (nbUVB) thrice weekly was initiated. Prednisolon was tapered during the first 2 weeks of phototherapy. Her skin began to improve slowly during nbUVB. At completion (20 sessions, 2 months), the rash had completely subsided leaving only hyperpigmented and hypopigmented macules. The patient was satisfied with the result and received her first COVID‐19 vaccination (Pfizer‐BionTech) 2 days later. She had no flare‐up after the first dose. However, she was given a second dose at her healthcare center 1 month later and a flare‐up of PLEVA occurred 10 days after the second vaccination, that is, 6 weeks after completion of phototherapy. The flare was milder but still affected the trunk and limbs and nbUVB was initiated again, with highly potent topical corticosteroid ointment.

Figure 1

(a) Extensive eruption on the back, consisting of papules, crusts and hypopigmented scars with a Christmas tree distribution. (b) Dark papules of the tights and legs.

Figure 2

Microscopic examination of skin biopsy shows necrosis of the epidermis, exocytosis of lymphocytes, lymphocytic infiltration of the upper dermis and numerous extravasated red blood cells (H&E, ×20).

Viral infections and vaccinations have been reported as possible triggers of pityriasis lichenoides (PL) in predisposed individuals. The occurrence of PLEVA in our patient could be fortuitous. She reported a sore throat 1–2 weeks after COVID‐19 infection and before the onset of PLEVA, but no other relevant viral infection was found as possible trigger. One case of PL chronica has been reported in a 42‐year‐old woman 10 days after COVID‐19 infection, and Guelimi et al have reported two patients with PL among French patients with unconfirmed COVID‐19 infection. A series of 10 children with a papulo‐purpuric rash with features of PLEVA have been reported among Italian paediatric COVID19 patients. Besides, three cases of PLEVA after SARS‐CoV‐2 vaccination have recently been reported: a 70‐year‐old man, a 31‐year‐old woman and a 81‐year‐old man developed PLEVA, 5, 10 and 9 days, respectively, after the second and first BNT162b2 vaccination (Pfizer‐BioNTech). Our case is specific as PLEVA occurred after a confirmed COVID‐19 infection and relapsed after the second, short‐interval vaccination, confirming thereby a link between SARS‐CoV‐2 infection and this inflammatory reaction.