Palmoplantar psoriasis is one of the more disabling variants of the disease. About 25% of patients with moderate to severe plaque psoriasis have palmoplantar psoriasis, and 20% of those who have predominantly palmoplantar psoriasis will have psoriasis elsewhere on their body, which may be just a plaque on the knee or in the scalp.1-3 There is a higher incidence of palmoplantar psoriasis in women and in smokers.1-3
Palmoplantar psoriasis has been defined as many different morphological subtypes. It can be thoroughly hyperkeratotic, with scaly red plaques; primarily pustular, which some consider a different entity called palmoplantar pustulosis; or a mixed texture of both hyperkeratotic plaques and pustulosis.3 It can affect hands only, feet only, or both regions.
Because of its location and often painful character, palmoplantar psoriasis can inhibit the ability to work or walk or complete activities of daily living. Additionally, it can be disfiguring and can create emotional distress for patients, particularly when patients have jobs that regularly involve handshakes or other interpersonal contact.4 Treating palmoplantar psoriasis can also be challenging for clinicians.
All the therapies that are appropriate for other forms of psoriasis can be used for palmoplantar psoriasis. Treatments include topicals and phototherapy, older drugs like methotrexate, cyclosporine, acitretin, and newer biologic and oral therapies. Often, these treatments do not work as well for psoriasis on the hands and feet as they do for other areas. For these reasons, the treatment of palmoplantar psoriasis is often challenging for both patients and physicians.
Treating With Topicals
Topical treatments are often the first-line option. Because palmoplantar disease only involves a limited area, topical treatment is quite feasible. Unfortunately, because the skin of the palm and sole is so thick, medications do not penetrate easily. Topical options include high-potency corticosteroids (eg, clobetasol and halobetasol); topical retinoids (eg, tazarotene); and other drugs—the topical vitamin D analogs and tacrolimus ointment/pimecrolimus cream and crisaborole (Eucrisa), both of which are off-label. The noncorticosteroid agents—topical retinoids, vitamin D products, tacrolimus and pimecrolimus, and crisaborole—generally work too slowly by themselves to be effective. They can be used adjunctively with other therapies such as topical corticosteroids, phototherapy, and/or systemic treatments.
UV Phototherapy and Combination Therapy
For various reasons, palmoplantar psoriasis often does not respond to topical therapies alone, so other treatments, including UV phototherapy, may be used. Hand and foot psoralen–UV-A (PUVA) may be preferred because the depth of penetration of UV-A is deeper than that of UV-B. Narrowband UV-B and excimer laser are also options. Narrowband UV-B or hand and foot PUVA can be combined with systemic treatments; acitretin is often a good choice for use in combination with phototherapy for palmoplantar psoriasis because acitretin thins the thick scale, making phototherapy more effective. Acitretin is also helpful for drying up the pustules seen in palmoplantar psoriasis.
Although psoriasis limited to the hands and feet may not involve a lot of surface area, palmoplantar psoriasis is considered moderate to severe because of its large effect on patients’ lives. Palmoplantar psoriasis is, therefore, generally an approved indication for treatment with systemic therapies.
Two of the oldest small-molecule drugs for psoriasis, methotrexate and acitretin, were compared in a study of 111 patients with palmoplantar psoriasis. More patients achieved a 75% reduction improvement with methotrexate.5 It may be chosen as a first-line therapy, in part because many insurance companies will not pay for more expensive treatments unless methotrexate is tried first. Methotrexate is associated with possible serious side effects, but it is well-tolerated by most patients.
When palmoplantar psoriasis affects the feet, it can inhibit the ability to walk or complete other routine activities.