Psoriasis and psoriatic arthritis (PsA) development is sustained by tumor necrosis factor (TNF)α, interleukin (IL)17, and IL23; hence, biologics targeting those cytokines represent useful therapeutic weapons for both conditions. Nevertheless, biologics strongly reduce PsA risk; several studies reported the possibility of new-onset PsA during biologic therapy for psoriasis. The aim of this 1-year prospective study is to evaluate the prevalence of paradoxical PsA in psoriasis patients under biologic therapy and review the existing literature. For each patient, age, sex, psoriasis duration, psoriasis severity, comorbidities, and previous and current psoriasis treatments were collected, and each subject was screened for PsA using the Early ARthritis for Psoriatic patient (EARP) questionnaire every 3 months for 1 year. New-onset PsA was diagnosed in 10 (8.5%) out of 118 patients (three male, 30.0%; mean age 44.5 years) involving every different biologic class (anti-TNF, anti-IL12/23, anti-IL17, and anti-IL23). No significant risk factor for new-onset PsA was identified; no significant difference was found comparing patients who developed PsA and subjects who did not develop PsA regarding psoriasis severity, past/current therapies, and comorbidities. Clinicians must keep in mind the possibility of PsA onset also in patients undergoing biologics so that PsA screening should be strongly recommended at each follow-up.

Androgenetic alopecia is the most common cause of hair loss [Br J Dermatol. 2011 Jan;164(1):5–15]. Finasteride and minoxidil are the only approved treatments [J Am Acad Dermatol. 2008 Oct;59(4):547–8 and J Eur Acad Dermatology Venereol. 2018 Jan;32(1):11–22]. Dutasteride is more potent than finasteride due to its ability to inhibit both 5-α-reductase type I and II [Our Dermatol Online. 2017 Sep;9(1):75–9] though its adverse effects and long half-life contribute to the reluctance on its oral use. Mesotherapy could be a feasible alternative to avoid systemic exposure and side effects [J Pan-Arab League Dermatologist. 2009 Feb;20(1):137–45]. We aim to perform a systematic review to analyze scientific literature with the purpose of comparing efficacy and adverse effects of both administration routes. Five clinical trials using oral route and 3 intralesional in comparison with placebo met criteria for inclusion. Regarding intralesional dutasteride, only one study [Clin Dermatol. 2001 Mar;19(2):149–54] reported the mean change in hair count. Although both interventions favor over placebo, there are not enough data to reliably compare outcomes obtained between both routes. Mean increase in hair count observed with oral dutasteride was higher (MD: 15.92 hairs [95% CI: 9.87–21.96]; p = <0.00001; I² = 90%) compared to intralesional dutasteride in Abdallah’s study (MD: 7.90 hairs [95% CI: 7.14–8.66]; p = <0.00001). Future studies are required to assess the therapeutic efficacy of both treatment routes, including head-to-head treatments before well-supported conclusions can be established.