Psoriasis: A Challenging Medical Condition

Introduction: Psoriasis is a common, non-infectious, chronic inflammatory skin disease characterised by distinctive erythematous plaques that multiply and scale over with silvery patches. Psoriasis can affect any cutaneous site and is frequently found on the extensor skin surface of elbows and knees, scalp and sacral region/s. Psoriasis is also associated with systemic conditions, including psoriatic arthritis, Crohn’s disease and lymphoma.

Epidemiology: Psoriasis is a common disease and is endemic across the world. It occurs in most racial groups. It affects approximately 2–5% of the population in Western countries. The severity of psoriasis varies greatly; about two thirds of people with psoriasis have a mild form (i.e., <3% of body area is affected), but others have more extensive involvement of the skin (>10% of body area is affected).

Diagnosis: Even 160 years after its identification, the diagnosis of psoriasis largely relies on clinical signs. In a normal clinical scenario, identification of psoriasis is straightforward, based on clinical signs such as sharp, demarcated, erythematous lesions with scaling plaques on body areas. In dubious cases, elbows and knees appear to be clear; however, careful examination of the scalp and intergluteal cleft normally show characteristic skin lesions. If the diagnosis is uncertain, typically a histologic confirmation (skin biopsy) and dermatology advice will be obtained.

Clinical management: Management of psoriasis is difficult because the distribution and severity of psoriatic plaques varies enormously. Mild psoriasis is often treated with topical preparations such as emollients, keratolytics, corticosteroids, tars, calcipotriol, dithranol and tazarotene. Moderate-to-severe psoriasis has traditionally been managed with systemic therapy such as methotrexate, acitretin and cyclosporine and phototherapy (ultraviolet B, psoralen plus ultraviolet A). Biologic agents such as adalimumab, efalizumab, etanercept and infliximab are generally reserved for systemic disease involvement. Current treatment options are only effective in reducing psoriasis symptoms temporarily. About 70% of subjects are said to prefer topical therapy for the management of psoriasis.