What is Psoriasis?
Psoriasis is a chronic, inheritable, noncontagious skin disorder. Plaque psoriasis is the most common type, with red raised plaques and silvery scale. It is most frequently found on the scalp, elbows, knees, and lower back. Itching and burning are common symptoms. A less common variant, pustular psoriasis, usually presents as pustules on the hands or feet but can involve the entire body.
When psoriasis involves the entire body, the condition is termed “erythrodermic psoriasis”. This can be a dermatologic emergency with patients experiencing high fevers, dehydration, and protein deficiency due to loss of skin scales. Occasionally, psoriasis involves skin folds (underarms, groin creases etc.) and is termed inverse psoriasis. Psoriasis limited to the scalp is termed seborrheic dermatitis. Guttate psoriasis presents as myriad tear-drop size papules, often following a strep throat infection. Psoriasis can also cause pitted nail plates or thickened crumbly nails with or without skin lesions (not all thickened yellow nails are caused by a fungus!). Furthermore, psoriasis can involve the joints, resulting in a destructive arthritis similar to Rheumatoid Arthritis.
What causes Psoriasis?
Over 7 million people in the United States are affected with this skin disorder and approximately 150,000 new cases are reported each year. The cause is unknown, though it is accepted as a genetic disease, inheritable from a parent or relative. One in three patients report a family history of psoriasis. Scientists believe that people with psoriasis have a limited immune system abnormality that leads to skin inflammation (redness, itching, pustules) and also an increase in the cell division rate of the epidermis (the epidermis being the top layer of the skin). Recent discoveries point to an abnormality in the functioning of special white cells (T-Cells) which trigger inflammation and the immune response in the skin. Because of the inflammation, the skin grows too rapidly. It normally takes 4 to 6 weeks for new cells to form and reach the top layer of the skin. A patient with psoriasis has skin cells that multiply so fast they can reach the epidermal surface in 7 days. Perhaps due to their rapid transit through the epidermis, psoriatic skin cells never form a normal skin surface. They pile on top of each other leading to the formation of thick scaly plaques.
What is the treatment for Psoriasis?
Treatment plans for psoriasis patients at our clinic are individualized and formulated based on the following factors: type of psoriasis, extent and severity, body locations, and the patient’s medical history, lifestyle, and age. Our goal is to reduce inflammation and slow down the abnormally rapid epidermal growth rate. Various treatment levels are available ranging from mild topical medications with limited side effects to powerful systemic drugs.
Level 1: Topical Medications
The first level of treatment involves the application of medications directly to the skin. This level of treatment is most practical for mild to moderate psoriasis. Topical Steroids are the most topical common therapy prescribed. Glucocorticoid steroids are primarily anti-inflammatory and can promptly reduce redness and itching as well as slowing down the growth rate of involved skin. Various strengths, ranging from mild to super potent, can be prescribed. Side effects are rare with appropriate use but include thinned skin, stretch marks and acne. Superpotent steroids can suppress natural hydrocortisone production. With prolonged use, steroids also tend to lose their effectiveness. For these reasons, we choose the strongest appropriate steroid and monitor for rapid response so the steroid cream can also be stopped. Also, oral steroids are never used in psoriasis due to the risk of a rebound flare. Sometimes lesions can be injected with steroids if only a few small lesions exist. Topical Vitamin D (Calcipotriene) is also effective as a topical medication along with Topical Vitamin A ( Tazorac), which is a retinoid compound. Both medications work primarily by reducing the production of new skin cells. While they tend to be slower in onset than topical steroids, they do not thin the skin or lose their effectiveness with prolonged use.
Level 2: Photochemotherapy
Natural sunlight has been used to treat psoriasis for decades. Certain wavelengths of ultraviolet light (UV) have also been proven effective. These selected spectrums of light are termed short-wavelength UV (UVB) and long wavelength (UVA). UVA is ineffective without the concomitant use of a medication called 8-methoxypsoralen (8-MOP), also called Oxsoralen Ultra. That is why tanning beds, which emit primarily UVA, are a poor treatment for psoriasis. The use of 8-MOP and UVA light is called PUVA and we have found this to be a very effective tool for inducing a remission of psoriasis. Photochemotherapy (PUVA) is one of the only treatments that can induce a remission of psoriasis. We also have a new generation UVB device that only generates a narrow band of UVB. This treatment, only recently imported from Europe, avoids potential complications of 8-MOP, and in some studies has equal efficacy as PUVA. By using only a narrow band rather than a full band of UVB, unnecessary UV exposure is eliminated. Though excessive UV light can cause photoaging and skin cancer, medically supervised administration of ultraviolet light is very safe and effective to control widespread or stubborn, unmanageable psoriatic lesions.
Level 3: Internal Medications
We tend to prescribe oral medications for severe cases of psoriasis that have been non-responsive to other treatment modalities. Patients are closely monitored to achieve the highest therapeutic response while minimizing potential side effects. Methotrexate is an oral anti-cancer drug that can produce dramatic clearing of psoriasis by slowing down skin cell growth. Acetritin is an oral retinoid that slows down epidermal cell rate division and is used for plaque-like psoriasis. However, Acetritin has many annoying side effects such as dryness, hair loss, and can cause birth defects. Cyclosporine is an immunosuppressant medicine that can dramatically reduce the inflammation within psoriatic lesions. Cyclosporine has one of the fastest treatment response-times of any drug for psoriasis and is especially useful for erythrodermic psoriasis. Unfortunately, all theses treatments have serious potential side effects, require intensive clinical and laboratory monitoring, and are expensive. Patients are closely monitored as we follow a rotational protocol and change these therapies every 6 to 12 months.
Level 4: Biomodulation
As researchers have discovered more biologic pathways that lead to psoriasis, they have bioengineered new medications that specifically target these pathways. Listed below are several of the biologic agents that are presently being used at Olympic Dermatology and Laser Clinic:
This is a biologic agent that blocks tumor necrosis factor-alpha (“anti-TNF”), thereby interfering with a key cytokine that contributes to the development of psoriasis. Etanercept has been approved for psoriasis since 2004 so has a long track of record of safe use. It is given by patients as an injection twice weekly for 12 weeks, then weekly as maintenance. It is effective for psoriatic arthritis too. While etanercept has many warnings, the major risk is a decreased ability for patients to fight off severe infections, especially tuberculosis.
This is another biologic agent that blocks tumor necrosis factor-alpha that was approved in 2008. Like etanercept it is given by patients as an injection, but is only injected twice a month. Adalimumab has a higher response rate then etanercept, at least initially, and is considered as safe as etanercept though with the same warnings. It is also effective for psoriatic arthritis.
This is a biologic agent that blocks immune mediators called interleukins, specifically interleukins 12 and 23. It is an injection given at our office by nursing staff, but only once every 12 weeks. It is the newest biologic agent, approved in 2009, but studies to date have not shown it to be any more dangerous then the other agents we use. Ustekinumab has a high response rate but it does not work as well for psoriatic arthritis. It has essentially the same warnings as the other biologic agents.
All the biologic agents require close clinical monitoring, intermittent lab testing, and yearly tuberculosis screening. They are not considered first-line therapies but are a very effective class of medications that we use regularly.