Essential Insights On Treating Psoriatic Lesions In The Lower Extremity

M. Joel Morse, DPM

   In plaque and palmoplantar psoriasis, the three pathogenic factors that we want to resolve are abnormal keratinocyte differentiation, epidermal hyperproliferation and inflammation of the skin. These three factors result in pruritus and burning.

   It is helpful to understand the traditional therapies used for psoriasis before we review the newer modalities. The oldest one is coal tar. It is a first line treatment for scalp, hand and foot psoriasis. It has anti-inflammatory, antibacterial, antipruritic and antimitotic effects. Coal tar has been in use for more than 100 years and was the mainstay for treating inflammatory skin conditions before the development of topical steroids.29

   The anti-inflammatory effects of tar are usually not as pronounced as those of topical glucocorticoids or calcineurin inhibitors. Tar preparations are useful in reducing the potency of topical glucocorticoids required in the long-term maintenance therapy of psoriasis.30

   Soaking the area in water seems too easy but superficial hyperthermia delivered biweekly via simple water bath immersion can clear mild to moderate psoriatic lesions. It can also reduce edema and relieve pruritus for up to several months.31

   Many individuals organize modalities into first, second and third lines of treatment. Emollients are a requirement in all of the different “tiers” of treatment. Emollients are the mainstay of all skincare regimens and help moisturize dry skin. In regard to psoriasis, emollients soften scaling and reduce irritation.13 Emollients are available as creams, ointments, lotions, shower gels, bath oils and aerosol sprays. They offer relief from dryness, scaling, itching and cracking, and may also have an anti-proliferative effect.

   First-line treatment involves topical therapies. Second-line therapy includes phototherapy and systemic drugs. Third-line treatment involves biologic therapy. If you are comfortable with systemic medications, including biologics, this is within the scope of our expertise. However, a dermatologist may have more practice with the systemic medications and biologics from his or her training.

A Guide To Topical Agents For Psoriasis

First-line options include keratolytics, topical corticosteroids, topical retinoids (vitamin A analogues), vitamin D analogues such as calcipotriol (Daivonex, CSL Biotherapies), calcitriol (Rocaltrol, Roche) or tacalcitol, and coal tar preparations.

   Keratolytics thin and soften the skin, and cause the stratum corneum to loosen and shed, removing the dead skin. Urea, salicylic acid and lactic acid are the more popular agents. These are present in many of the products we use such as Foot Miracle (Foot Miracle), 45% urea nail gel (Uramaxin, Medimetriks Pharmaceuticals) and Kerasal (Alterna). Use these at low concentrations for general thinning of skin.

   Calcipotriene 0.005% (Dovonex, Warner Chilcott) is a vitamin D3 analogue that inhibits epidermal cell proliferation and enhances cell differentiation. It is available as a cream and recently came out as a foam. Most studies show that calcipotriene is not as effective as group I corticosteroids but regimens using calcipotriene and group I corticosteroids are superior over either agent alone.32

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