Scalp psoriasis

What is scalp psoriasis?

Scalp psoriasis is a skin condition characterised by red, thickened, well-demarcated patches or plaques with overlying silvery-white scales, affecting part or all of the scalp.

It can be contained within the hairline, though frequently affects the back of the head, or extends onto the forehead (facial psoriasis), ears, or neck. While often camouflaged by the hair, scalp psoriasis can be a source of embarrassment and distress due to itching and dandruff-like flaking. It may occur in isolation, or with any other form of psoriasis, and is typically a chronic, relapsing-remitting condition.

Scalp psoriasis extending beyond the anterior hairline 

Confluent psoriasis in the scalp extending anteriorly from the hairline 

Marked thick scaling in psoriasis of the scalp 

Extensive scaling over the parietal scalp due to psoriasis. There is psoriasis also in the ears and around the hair line 

Marked scaling in psoriasis of the scalp 

Severe scalp psoriasis with areas of pityriasis amianticea 

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Who gets scalp psoriasis?

Psoriasis is estimated to affect 2% of the population worldwide and can occur at any age. Among those affected by psoriasis, approximately 80% experience scalp involvement.

What causes scalp psoriasis?

In psoriasis, skin cells tend to form quickly (hyperproliferation), within days rather than weeks, due to faulty immune system signals. As a result, excess cells pile up on the skin surface, causing patches and plaques.

Psoriasis, including scalp psoriasis, is thought to be caused and affected by a combination of genetic, immune, hormonal, and environmental factors, such as:

• Bacterial infections, such as streptococcal sore throats
• Human immunodeficiency virus (HIV) infection and acquired immunodeficiency syndrome (AIDS)
• Hormonal changes (psoriasis often intensifies around puberty, the postpartum period, and menopause; and often improves during pregnancy)
• Sunlight/ultraviolet radiation — usually helps but occasionally exacerbates psoriasis
• Use of harsh chemical products or soaps
• Stress
• Obesity
• Trauma or injury to the skin (Koebner phenomenon)
• Cigarette smoking
• Alcohol consumption
• Medication — this may induce or exacerbate psoriasis.

What are the clinical features of scalp psoriasis?

• Scalp psoriasis is characterised by well-defined, red, thickened patches or plaques on the scalp with overlying silvery-white scales.
• Scales can flake off causing ‘dandruff’.
• It can be localised to parts of the scalp and often affects the back of the head, or can involve the entire scalp.
• It can be very itchy
• Scaling may build up and produce an appearance similar to overlapping Mediterranean roof tiles (Pityriasis amiantacea)
• In severe cases, scalp psoriasis can be associated with temporary localised hair loss (alopecia).

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How do clinical features vary in differing types of skin?

According to Gelfand et al (2005), the prevalence of all psoriasis was 1.3% in black patients compared to 2.5% in white patients, which is probably linked to genetics.

However, the diagnosis of psoriasis may also be delayed or missed in darker skin phototypes where the presentation of psoriasis may vary from purple to dark brown patches with grey or silver scales.

When managing scalp psoriasis in patients with different skin and hair types, it is important to formulate a topical treatment regimen that is compatible with each patient’s hair care practices and cultural preferences. For example, hair texture that requires a reduced frequency of hair washing thereby renders daily medicated shampoos unsuitable. Once weekly washing in conjunction with daily application of a topical corticosteroid in a vehicle compatible with preferred hair styling practices may be more acceptable.

What are the complications of scalp psoriasis?

• Dry itchy scalp.
• Sleep disturbance secondary to itching.
• Skin infections due to scratching and impaired skin barrier.
• Anxiety and reduced self-esteem due to scalp appearance and dandruff-like flaking.
• Reversible hair loss (alopecia).
• Rarely, scarring alopecia can develop due to chronic, relapsing scalp psoriasis.
• Scalp psoriasis may be associated with psoriatic arthritis (PsA).

How is scalp psoriasis diagnosed?

Scalp psoriasis is generally diagnosed clinically. Key trichoscopic findings include red dots, hairpin vessels, and red globular rings (for more information, see trichoscopy of inflammatory conditions). A skin biopsy may be performed in some cases to confirm the diagnosis.

Additionally, assessing psoriasis severity — for example, using the Psoriasis Scalp Severity Index (PSSI) — and its impact on quality-of-life is important.

What is the differential diagnosis for scalp psoriasis?

• Seborrhoeic dermatitis — can co-exist with scalp psoriasis (called sebopsoriasis).
• Fungal scalp infection (tinea capitis).
• Pityriasis amiantacea
• Pityriasis rubra pilaris.

What is the treatment for scalp psoriasis?

Scalp psoriasis can be difficult to treat due to the delivery of therapy in and around the hair, which complicates the application of many topical products. Cosmetic considerations also affect treatment adherence.

Usually, lotions, solutions, or gels are more suitable for the scalp than heavier products such as ointments. In recent years, a number of new formulations have been developed (eg, foams, shampoos, and sprays) that enhance cosmetic acceptability and adherence. Most treatments will need to be used regularly for several weeks before a benefit is seen, and may have to be applied regularly to keep the scalp clear.

See Treatment of psoriasis for more information.

General measures

• Regular use of emollients and moisturisers such as scalp oils.
• Avoiding known triggers where possible.
• Modifiable lifestyle factors such as maintaining a healthy weight, limiting alcohol intake, and smoking cessation.
• Avoiding picking or scratching the scalp, which can cause further damage.
• Some people find cutting their hair short helps control scalp psoriasis, likely as it makes treatments easier to apply.

Specific measures

Topical medications are recommended as first-line treatment of mild-to-moderate scalp psoriasis, and can also be used concomitantly with phototherapy and/or systemic therapies in moderate-to-severe cases.

Topical agents

• Topical corticosteroid is recommended for short-term treatment (eg, clobetasol propionate 0.05% shampoo, steroid foams, water-based gels, scalp applications); there is limited data on long-term monotherapy for the scalp.
• Topical Vitamin D analogues eg, calcipotriol — unlike steroids, these do not cause skin atrophy; however, they are found to be less effective than corticosteroids for scalp psoriasis (also not recommended for use on the face).
• Combined corticosteroid and Vitamin D therapies eg, calcipotriol 0.005% and betamethasone dipropionate 0.05% gel has been found to be superior to its individual ingredients, with a fast onset of action and no reports of skin atrophy, striae, purpura, or significant effects on serum calcium.
• Keratolytic (anti-scaling) agents, eg, salicylic acid, urea, or a dimethicone-based topical keratolytic spray (eg, Loyon®)
  • Salicylic acid shampoos can enhance the penetration of other topical treatments including corticosteroids, and have been recommended by the US National Psoriasis Foundation.
• Coal tar shampoos (2–10%) — coal tar can be very effective for body psoriasis although less evidence for use in scalp psoriasis, and less cosmetically acceptable as can stain the scalp and hair.
• Coconut oil compound ointment (eg, Coco-Scalp®) — a combination of coal tar, salicylic acid, and sulphur that can be left on for at least an hour (or even overnight) before being shampooed off. Compliance can be aided by watching an instructional video on its application and use (see Treating scalp psoriasis linked below).
• Ketoconazole, ciclopirox, zinc pyrithione, and other antifungal shampoos — effective for dandruff and seborrhoeic dermatitis; varying effect on sebopsoriasis and psoriasis.

Less commonly used topical therapies

• Intralesional corticosteroids — have been applied in practice and remain a second-line treatment option, although specific studies evaluating this treatment regimen for scalp psoriasis are lacking.
• Dithranol — a ‘short contact’ cream. Less commonly used now but can produce long remissions. Can cause irritation and staining; avoid in those with grey or blonde hair.

Phototherapy

• Targeted phototherapy with a laser or non-laser light source can help improve symptoms.
• Can be challenging to target the scalp in the presence of hair.
• Direct treatment may be helped by a handheld ultraviolet B (UVB) comb device.

Systemic agents

Consider first-line for patients with scalp psoriasis and accompanying moderate-to-severe whole-body psoriasis; and second-line in other cases where there has been an inadequate response to topical therapy.

• Immunosuppressants such as methotrexate and ciclosporin.
• Vitamin A derivative acitretin.
• Phosphodiesterase-4 (PDE4) inhibitor apremilast.
• Biologic agents such as anti-TNF, IL-17 and IL-12,-23 inhibitors (eg, etanercept, adalimumab, infliximab, brodalumab, secukinumab, ixekizumab, ustekinumab, guselkumab, risankizumab, and others.

Support groups can also be helpful for those living with psoriasis.

How do you prevent scalp psoriasis?

Scalp psoriasis tends to be a chronic problem. However, regular scalp care, maintenance treatment, lifestyle factors, and avoiding triggers or exacerbating factors can help prevent or reduce the severity of flares.

What is the outcome of scalp psoriasis?

While scalp psoriasis is generally a chronic, relapsing-remitting condition, there are many available treatment options. The mainstay of treatment is topical therapy, although this can be challenging for scalp conditions given their location and the presence of hair.

Newer topical formulations, such as foams and sprays, can help to improve treatment tolerability and outcomes. In patients with moderate-to-severe disease who do not respond to topical treatments, there are a number of systemic therapies including immunomodulatory agents and biological treatments.

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