Psoriasis presents as well-circumscribed, erythematous plaques with an overlying silvery white scales. It has an effect on various aspects of life including mental health, productivity and relationships.~Topical therapies as corticosteroids and vitamin D3 analogs are first-line treatments for mild plaque psoriasis; which involves less than 3% of the body surface area (BSA). Moderate-to-severe plaque psoriasis is usually managed with phototherapy, systemic or biologic therapies .~The American Academy of Dermatology gives a strength recommendation for the use of combination therapies for treatment of psoriasis with superior efficacy to monotherapy .~The 308-nm excimer laser has been widely used for many dermatological diseases. In psoriasis, it shows an efficacy in the treatment of localised plaques especially on the knees and elbows.~It is indicated in moderate to severe psoriasis that affects <10% of the body surface. Areas such as nose, ears and palpebral region can be easily accessed using the laser. It induces lymphocytic apoptosis and decreases the proliferation rate of keratinocytes . There are multiple protocols that evaluate the clinical response to Excimer laser; the induration protocol, the minimal erythema dose and the minimal blistering dose.~The induration protocol compared with the others, allows to modify the dose with treatment. With this protocol, plaques achieved Psoriasis area and severity index (PASI-75) after 10 treatments .~Tazarotene (TAZ) is a topical retinoid with retinoic acid receptor β / γ receptor specificity. It has been shown to be effective for psoriasis treatment. However, its topical application is limited by its irritation.~Studies have shown that combination with other lines may optimize the efficacy as well as minimize the local irritation due to TAZ.~Betamethasone valerate (BV) is a high-potency, synthetic corticosteroid which acts on the intracellular glucocorticoid receptor.~It also binds to membrane-bound receptors, enhancing its action. BV suppresses the production of inflammatory cytokines and reduces keratinocyte hyperproliferation.
Psoriasis is a chronic, immune-mediated disease that affects approximately 2% of the population. The development and exacerbation of psoriasis involve an interaction between multiple genetic and environmental risk factors.