Acute onset of psoriasis in a patient with atopic dermatitis treated with dupilumab

Atopic dermatitis (AD) is a chronic, multifactorial, inflammatory skin disease that can have a negative impact on patient quality of life (QoL). Moderate to severe forms frequently require systemic treatment. Dupilumab is a human monoclonal antibody directed against the alpha subunit of the interleukin (IL)‐4 receptor. It was the first biologic drug approved for the treatment of moderate to severe AD. The data available regarding efficacy and safety are from clinical trials, and show a good safety profile with fewer adverse effects (AEs) recorded in the literature, especially for ocular involvement. We report a case of psoriasis developing during dupilumab treatment. A 42‐year‐old man presented with AD that had been present since childhood, associated with allergic rhinitis and elevated total serum IgEs. No personal or familiar history of psoriasis was reported. Based on the Hanifin and Rajka clinical criteria and the histological diagnosis of spongiotic dermatitis, we made a diagnosis of severe AD uncontrolled by topical and traditional systemic treatments, including ciclosporin. The patient was started on dupilumab in accordance with the dose regimen for AD [600 mg subcutaneously (SC) injection at week 0, followed by 300 mg SC every 2 weeks] and the AD progressively improved. Within 4 weeks of therapy, all clinical scores improved, along with scores for QoL: Eczema Area and Severity index 7 (vs. 43 at baseline), Investigator’s Global Assessment 1 (vs. 4), Dermatology Life Quality Index 3 (vs. 13), Patient‐Oriented Eczema Measure 5 (vs. 26), Pruritus/Itch Numeric Rating Scale (NRS) itching 4 (vs. 10) and NRS sleep disturbance 4 (vs. 8). The patient was referred to us 3 months into dupilumab treatment due to the sudden onset of diffuse erythematous and scaly plaques on the trunk and limbs (Fig. 1). Punch biopsy of a new lesion was performed and histological diagnosis of psoriasis was made. (a) Cutaneous lesions of atopic dermatitis at the beginning of treatment with dupilumab; (b) multiple erythematous and scaly plaques on the trunk arising 3 months after starting dupilumab. Dupilumab was discontinued, and the patient was treated with topical calcipotriene and betamethasone dipropionate foam, achieving clinical remission in about 40 days. Only a mild recurrence of the AD was noted after 2 months from the withdrawal of dupilumab. AD and psoriasis can be considered two opposite poles of the cutaneous manifestations of T‐helper (Th) cellular‐mediated inflammation; on the one hand, activation of the Th1 cascade with its correlated cytokines and cell subsets (such as Th17 and Th22) has a predominant role in the pathogenesis of psoriasis, while on the other hand, the Th2 cascade and its cytokines are involved in the pathogenic mechanisms of AD.1 Psoriasis is considered primarily a Th17‐driven disease with increased levels of related interleukins (IL‐17A, IL‐22 and IL‐23), whereas AD is a Th2 cellular‐mediated disease with a predominance of IL‐4 and IL‐13, which are able to drive the differentiation of IL‐4 and stimulate production Th2 cells from naive T cells in all allergic diseases. Recently, some studies have underlined the negative regulatory action of IL‐4 on the Th1 pathway; it rescues IL‐23 production2 and silences the Th17‐dominated skin inflammation that is predominant in psoriasis. Consequently, it is thought that inhibition of the Th2 pathway through blockage of IL‐4 and IL‐13 signalling could play a role in a shift toward the Th1 inflammatory pathway, which may be responsible for the development of psoriasis in genetically predisposed patients treated with dupilumab.1 Our case represents one of the few reported clinical cases of psoriasis arising during dupilumab therapy in the literature.3‐5 To our knowledge, no cases of psoriasis, either new presentation or exacerbation, were recorded during preliminary studies of dupilumab. Post‐marketing surveillance and long‐term treatment and monitoring will hopefully clarify this possible relationship. Conflict of interest: the authors declare that they have no conflicts of interest.