Psoriasis

Psoriasis is a common, chronic, relapsing skin disorder that is characterized by epidermal hyperproliferation and dermal inflammation.  The most common form, plaque psoriasis, affects about 1 to 2% of the American population.  Plaques are scaly circular-to-oval red lesions that occur typically on knees and elbows or other extensor surfaces of the skin as well as the scalp.  In some cases, nail changes can be observed such as pitting, separation of the nail plate (onycholysis), and excessive proliferation of the nail bed (subungual hyperkeratosis).  The extend and duration of the disease is highly variable from patient to patient and often triggered by environmental factors such as trauma and sun exposure, as well as alcoholism, smoking, and infection.  There are a number of genetic factors that have been associated with plaque psoriasis but specific inheritance mechanisms have yet to be elucidated.  About 10 to 20% of patients experience psoriatic arthritis.

Patients suffering from plaque psoriasis experience extensive itching, dry and peeling skin, and fissuring.  Self-consciousness and embarrassment, inconvenience, and the high cost of antipsoriatic treatments also severely affect the patient’s quality of life.
Psoriasis is generally classified as mild-to-moderate (up to 20% of body surface involvement) and severe (> 20 % of body surface involved).  A number of effective systemic treatments (including biologics) are available for severe psoriasis.  However, these treatments are not suitable for milder cases due to potential side affects and high cost.  Phototherapy is a commonly chosen as an alternative but is limited by time commitment and accessibility of the equipment.  Topical treatments for psoriasis are available but no single agent is ideal and the most effective treatments involve prolonged administration of topical corticosteroids which can lead to skin atrophy and systemic side effects.  Rebound flares are often observed when topical corticosteroid treatment is discontinued.

More information about psoriasis can be found at the National Psoriasis Foundation (www.psoriasis.org).