Scalp Psoriasis

Picture of scalp psoriasis. Source: iStock.com.

Psoriasis is an inflammatory disease of the skin that is estimated to affect about 2.2% of the adult population. In children, the onset of psoriasis can be before the age of one year but peaks around 5-8 years. Psoriasis produces scaly, itching bumps on the skin. It appears as red scaling, slightly raised bumps (papules) that merge to form plaques.

Some people may have a genetic predisposition to psoriasis. The genes affected seem to be involved with the control of the immune system.

Psoriasis classically appears on the elbows and knees, but it can affect any part of the skin. The scalp is also characteristically affected in many people. Like psoriasis anywhere on the body, scalp plaques produce excess scale and can itch. Severe disease can cause a loss of scalp hair, which usually will return if the disease can be controlled.

Scalp psoriasis is somewhat difficult to treat when the scalp is covered with hair sufficient to act as a barrier to the application of topical medications.

Occasionally, seborrheic dermatitis of the scalp can be confused with scalp psoriasis since both can produce excess scale and can itch. Pathological examination of the skin biopsy material occasionally may help distinguish the two entities. As a practical matter, this is rarely necessary because most patients with psoriasis have typical psoriatic lesions present in other areas, such as the elbows, knees, or torso. In addition, both conditions generally respond to similar topical medications.

It is generally accepted that scalp psoriasis, like all psoriasis, is related to genetic defects that affect certain parts of the immune system. There are undoubtedly environmental risk factors that trigger its initial development in genetically predisposed individuals.

The notion that "emotional stress" plays a causal role or at least exacerbates psoriasis has been difficult to prove. There is no question, however, that psoriasis of the scalp can be an extremely stressful experience.

Psoriasis appears as a small bump, a papule, surmounted by scale. When these papules coalesce, a plaque is formed that is often covered by thick layers of horny scale. When this scale is shed, it appears as dandruff, which can be quite unsightly.

Scratching these plaques, either because of itching or because of the impulse to remove them, is a very poor idea because of what is called the Koebner phenomenon (also known as the Koebner response or isomorphic response). This may cause psoriasis to develop in areas of inflammation and trauma. Scratching off the scale will only make things worse.

Although most patients do not note hair loss, there can be extensive alopecia hair loss (alopecia) in severe cases.

Dermatologists are specialists who deal with the diagnosis and treatment of many kinds of scalp conditions. Other physicians that can be involved in the care of patients with psoriasis include general and family-practice physicians, internists, and rheumatologists.

The fact that the scalp is a hair-bearing area in most people produces challenges in diagnosis as well as treatment. If scaling plaques are present on portions of the body in a distribution characteristic of psoriasis, then the diagnosis of scalp disease is much easier to make.

The most important consideration in treating scalp psoriasis is getting an effective medication into the skin. Both the hair and any scale covering the disease act as an impediment to treatment. Removal of the scale in a nontraumatic fashion is very important. This can be accomplished by shampooing frequently. Using tar, selenium, or salicylic acid-containing shampoos can be helpful. This may have to be done at least twice a day initially if the scale is sufficiently thick. Gently rubbing off the scale with the fingertips and not the nails is important.

It should be appreciated that scaling is not due to dryness but to the excessive production of the horny layer of the skin. Occasionally, it may be necessary to cover the scalp overnight with mineral oil. To avoid an unpleasant mess, it is necessary to cover the head with a shower cap or swim cap.

With moderate or severe scalp disease, the addition of a topical steroid is often required. The potency of the steroid would depend on the severity of the condition. The type of vehicle (lotion, solution, or foam) depends on physician and patient preference. It is important to remember that the medication must get past the hair to reach the scalp skin.

Sometimes other medications may be of benefit, such as topical calcipotriene (Dovonex, Sorilux) in a lotion or foam form. Some medications are available as combinations of topical steroids and calcipotriene.

If the scalp is involved as part of severe psoriasis deemed too extensive to be treated practically with topical medications, then medications delivered orally or by injection may be necessary. All these medications comprise more risk when compared to topical medication. They include oral drugs like methotrexate (Rheumatrex, Trexall), cyclosporine (Sandimmune), acitretin (Soriatane), apremilast (Otezla), and some of the so-called biological drugs that are administered by infusion into a vein (infliximab [Remicade]) or by injection into the deeper layers of the skin like etanercept (Enbrel), adalimumab (Humira), ustekinumab (Stelara), secukinumab (Cosentyx), and ixekizumab (Taltz).

Regular laboratory work may be necessary to monitor for the toxicities associated with some of these systemic therapies.

Rarely, it may be of benefit to inject triamcinolone acetonide directly into psoriatic plaques. Aside from the pain involved, the benefit only lasts about six weeks at best. Ultraviolet light in wavelengths near 313 nm (narrow band UVB) is effective in psoriasis. The hair, however, can pose a barrier to effective administration unless it is removed or sparse. The excimer laser produces laser light in these UV wavelengths also and can be of benefit if the amount of scalp involvement is limited.

Since psoriasis is incurable unless there is a miraculous spontaneous resolution, those afflicted need to remember that constant care is required to keep it controlled. With diligent attention, scalp psoriasis can be controlled.

Patient support groups like the National Psoriasis Foundation are valuable additions to medical care that can aid individuals dealing with the disease.