Scalp psoriasis

What is scalp psoriasis?

Psoriasis is a common skin condition, characterised by red scaly thickened patches (plaques). It ofen affects the scalp. Scalp psoriasis may occur in isolation or with any other form of psoriasis.

The back of the head is a common site for psoriasis, but multiple discrete areas of the scalp or the whole scalp may be affected. Scalp psoriasis is characterised by thick silvery-white scale over well-defined red thickened skin. Psoriasis may extend slightly beyond the hairline (facial psoriasis).

Scalp psoriasis, even though often adequately camouflaged by the hair, is often a source of social embarrassment due to flaking of the scale and severe 'dandruff'. Scalp psoriasis may not cause any symptoms at all or may be extremely itchy. It tends to be a chronic problem, lasting many years, although it often fluctuates in severity and extent.

In very severe cases there may be some temporary mild localised hair loss but scalp psoriasis does not cause permanent balding.

Scalp psoriasis

© Dr Ph Abimelec – dermatologue

More images of scalp psoriasis ...

Sebopsoriasis

Sebopsoriasis is an overlap between psoriasis and another common skin condition, seborrhoeic dermatitis. There tends to be less silvery scale than psoriasis and more yellowish, greasy scale.

Sebopsoriasis tends to localise to the scalp, face and anterior chest in a similar pattern to that seen in seborrhoeic dermatitis. But sebo-psoriasis has a deeper red colour, more defined margins and a thicker scale than typically seen in seborrhoeic dermatitis alone. It is also less likely to clear up with anti-dandruff shampoo.

Pityriasis amiantacea

Pityriasis amiantacea is characterised by thick, yellow-white scales densely coating the scalp skin and adhering to the hairs as they exit the scalp. The scales are arranged in an overlapping manner like tiles on a roof or flakes of asbestos, hence the name. The underlying scalp skin may appear normal, aside from the scale, or may be reddened or scaly. Pityriasis amiantacea is often present without any obvious underlying cause, but may be associated with psoriasis, seborrhoeic dermatitis or lichen simplex (another form of dermatitis).

Pityriasis amiantacea usually affects only part of the scalp but may occasionally involve the whole scalp.

Some hair loss is common is areas of pityriasis amiantacea. The hair regrows normally if the condition is effectively treated. Hairs may be pulled out by combing due to the very adherent, thick scale at the base of the hair shafts. If additional complications such as infection occur then hair loss may be associated with scarring but bald areas are rarely permanent.

The term tinea amiantacea is incorrect, because fungal infection, tinea capitis, is a very rare reason for this type of scaling.

Scalp care

Scalp psoriasis requires slightly different regimes from psoriasis affecting the skin elsewhere. This is due to hair, which makes application of many topical products difficult and protects the scalp from the effects of ultraviolet light. Unfortunately, many scalp treatments for scalp psoriasis are messy and smelly. Most treatments will need to be used regularly for several weeks before a benefit is seen.

Special medicated shampoos can be purchased from the chemist.

• Coal tar shampoos are suitable for most patients with scalp psoriasis.
• Ketoconazole, ciclopirox, zinc pyrithione and other antifungal shampoos are effective for dandruff and seborrhoeic dermatitis. They have varying effect in sebopsoriasis and psoriasis.

The shampoos work best if rubbed into the scalp well, and left in for 5 or 10 minutes and then reapplied. They are safe for daily use but may irritate if applied more than twice weekly. If you dislike the smell of coal tar, try shampooing again with a favourite brand, and use a conditioner.

More severe cases require leave-on scalp applications.

• Alcohol-based, foam, gel or lotion forms of topical steroid and calcipotriol can reduce redness and itch but they don't lift scale very well. Use topical steroids intermittently; overuse results in more extensive and severe psoriasis.
• Salicylic acid and coal tar creams work much better, but are messy. Coconut oil compound ointment is a combination of coal tar, salicylic acid and sulphur and seems particularly effective. Leave on for at least an hour and shampoo off later. Most people rub the cream into the plaques at night and wash it off in the morning.
• Dithranol may be effective but is difficult to use and may be messy as it stains hair and fabrics.

Use the scalp preparation daily at first then as the condition improves, reduce the frequency. Unfortunately in many cases the scale soon builds up again, so the creams may have to be applied regularly to keep the scalp clear. Topical steroids are best used only 2-3 times weekly, long term to avoid complications.

Cutting hair short helps control scalp psoriasis, probably by making the treatments easier to apply, but is not appealing to everyone.

Phototherapy is effective for chronic plaque psoriasis but difficult to deliver to the scalp. Special targeted devices and UVB combs have been devised, and appear very helpful. In some cases prolonged clearance has resulted from a course of treatment.

Systemic agents may be justified for a few patients with severe scalp psoriasis that has failed to respond to treatments described above. These include acitretin, methotrexate, ciclosporin and biologic agents.