Treating Psoriasis In The Lower Extremity

Tracey C. Vlahovic, DPM

In addition to reviewing the clinical presentation of psoriasis in the lower extremity, this author provides key insights on various topical medications ranging from corticosteroids and vitamin D analogs to retinoids and keratolytics. She also offers insights on systemic therapies that physicians may consider when the disability and disease severity warrant a more aggressive approach.

Psoriasis is a chronic, inflammatory, immune mediated skin disorder with extensive ongoing research dedicated to therapies that target specific pathways and immune mediators. Psoriasis occurs in 2.6 percent of the population in the United States.1 Given the numerous therapies available, choosing the optimal course of treatment can be overwhelming for the practitioner.

   Accordingly, let us take a closer look at key clinical considerations in managing plaque psoriasis and review the current and emerging topical medications.
The most common presentation is an erythematous plaque with silvery scales that is well defined geographically and symmetrical across the extremities. In the podiatric patient, the most common presentation is the palmar-plantar type, which typically presents on the volar surfaces of the hands and feet. These skin lesions may cause pain, pruritus, irritation, inflammation and fissuring. In addition to the clinical symptoms, patients may suffer from the psychological aspects of having a skin disease, which causes difficulty in performing activities of daily living as well as a feeling of being “contagious” to other people.

   Not only is psoriasis a disabling skin disease, it also predisposes the patient to systemic disorders collectively known as metabolic syndrome.2 Patients have a higher risk of developing comorbidities, such as diabetes, hypertension, hyperlipidemia and obesity, that may ultimately lead to heart disease. Accordingly, patients who have psoriasis have a greater risk of developing a myocardial infarction.3 Both the clinical (pain and deformity) and psychological (depression and anxiety) repercussions of the disease may lead to smoking, drug use, alcohol abuse and obesity that further contribute to the risk of developing cardiovascular disease.4

   The extent to which physicians can decrease the long-term effects of the metabolic syndrome is yet to be quantified in patients with psoriasis. For now, increasing quality of life and decreasing disability should be the ultimate goals.

What To Expect From The Patient Presentation

Patients will generally present with itchy, dry skin plantarly that may fissure, develop small pustules or be well defined erythematous patches. The pattern may include the whole plantar aspect, only the non-weightbearing surfaces or only the weightbearing surfaces. The scale can range from being limited to the skin lines and appearing as generalized xerosis to a fine silvery micaceous covering over a geographic plaque.

   Unfortunately, due to the prevalence of the scale, the most common misdiagnosis for plantar psoriasis is tinea pedis. In this case, patients will receive a prescription for a topical antifungal or purchase an over-the-counter (OTC) agent that will not work to their satisfaction. Patients will express their frustration with their current antifungal therapy and most likely not consider the possibility of psoriasis occurring on the feet.

   If the practitioner suspects psoriasis, there are several questions the physician and the patient can answer.

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