Psoriasis of the Scalp

G.D. Schachter, MD

Division of Dermatology, Sunnybrook & Women’s College Health Science Centre, Toronto, ON, Canada

The Disease

Psoriasis is a chronic, unpredictable, T cell mediated, inflammatory, papulosquamous
condition that affects approximately 2%-3% of any population.

• The average age of onset is mid- to late-20s, although onset may occur at any age.
• Psoriasis is characterized by accelerated proliferation of epidermal cells (keratinocytes), vascular proliferation, and an influx of inflammatory cells (neutrophils, macrophages, and activated T cells).
• Involvement of the scalp may be minimal (few plaques) or more significant. The entire scalp can be involved.
• Hair loss may be seen with significant involvement of the scalp, and is non-scarring. Hair should regrow when the psoriasis clears.

Areas Affected

Psoriasis affects the skin, especially extensor surfaces and also the scalp, body folds, and nails. The scalp may be the most frequently involved area. Approximately 15%-30% of patients have an associated arthritis.

Cause

There is a genetic basis to psoriasis with an increasing risk of developing the disease if one or both parents have psoriasis. The activated T cell plays a pivotal role in the pathogenesis of the disease.

Symptoms

• Itch
• Psychosocial distress (markedly affects quality of life)
• Hair loss with severe involvement

Classic Lesion

The classic lesion is a well-demarcated, erythematous plaque with a silvery scale. When the scale is removed, bleeding points are seen (Auspitz sign). Psoriasis can develop after trauma and lesions worsen with rubbing or scratching (Koebner phenomenon).

Forms/Types of Lesions

• Chronic Plaque
• Erythrodermic
• Pustular – Localized or Generalized
• Guttate
• Inverse

Triggers

• Stress
• Hormones – Pregnancy
• Trauma
• Drugs – Beta-Blockers, Lithium, Anti-Malarials
• Systemic Steroid Withdrawal
• Infections – Viral and Streptococcal

Differential Diagnoses

• Seborrheic Dermatitis – common
• Lichen Planus – unlikely
• Fungal Infection – unlikely
• Lupus Erythematosus – unlikely

Scalp Psoriasis vs. Scalp Seborrheic Dermatitis

Seborrhiasis

Seborrhiasis presents with features of both psoriasis and seborrheic dermatitis. Psoriasis of the scalp is primarily treated locally with topical treatments. Systemic therapies are usually reserved for more widespread or severe forms of psoriasis.

Recalcitrant Psoriasis

Resistant or recalcitrant psoriasis of the scalp may require intralesional injections of corticosteroids, and less frequently a systemic treatment.

Treatments for Psoriasis

Topicals

• Tar
  • Coal Tar
    – Shampoo
    – Compounded with corticosteroids
  • Wood Tar
    – Anthralin (Infrequently used in North America; still popular in Europe)
• Corticosteroids
  • Lotion (e.g., betamethasone valerate)
  • Gel (e.g., fluocinonide)
  • Foam (Not available in Canada)
  • Shampoo (e.g., clobetasol propionate (Clobex®))
  • Oil and Corticosteroid (Dermasmoothe® FS oil)
• Vitamin D3 Analogues
  • Calcipotriol (Dovonex® Scalp Solution)
  • Calcipotriol + betamethasone dipropionate (Dovobet®)
• Salicylic Acid 5%-15% in mineral oil
• Shampoos
  • Tar (T-Gel® or Sebcur T®)
  • Salicylic Acid (Sebcur®)
  • Zinc Pyrithione (Dangard® or Head & Shoulders®)
  • Ketoconazole (Nizoral®) or Ciclopirox (Stieprox®)
  • Potent Corticosteroid (Clobex®/Clobetasol®)

Ultraviolet Light

• UVB
• Narrow Band
• PUVA – oral, bath, soaks
• Phototherapy (Rarely used for scalp) – Innovative “comb” to deliver ultraviolet light

Systemic Treatments

• Acitretin (Neotigason®)
• Methotrexate
• Cyclosporin – A
• Biologics
  • Alefacept (Amevive®)
  • Etanercept (Enbrel®)
  • Efalizumab (Raptiva®)

Intralesional Corticosteroid Injections (Triamcinolone / Kenalog Injections)

Combination or Rotational Treatments

Key Points

Mild-to-moderate cases of scalp psoriasis

• Gently shampoo scalp every morning (use palms NOT fingertips)
• Apply a corticosteroid gel or lotion once or twice per day
• Apply calcipotriol (Dovonex®) solution once or twice per day
• Antihistames (hydroxyzine or doxepin) at night for itching

Moderate-to-severe cases of scalp psoriasis

• Apply oil and salicylic acid or Dermasmooth FS® oil at bedtime and wear a shower cap
• Resistant plaques can be injected with Triamcinolone 2.5-4 mg/u every 3 or 4 weeks as necessary
• Antihistamines (hydroxyzine or doxepin) at night for itching

It should be noted that rarely scalp psoriasis is severe enough to require systemic agents such as methotrexate or acitretin.

Warnings

• Do not rub, scratch, pick, or brush/comb roughly.
• Treat gently.
• Do not pick off scale.
• Moisturize.
• Trauma or surgery will cause the plaques to flare (thicker, scalier plaques, larger areas).

Conclusion

Psoriasis remains a therapeutic challenge. Involvement of the scalp can be minimal (“dandruff”) or more significant and difficult to manage. Gentle treatment, reducing trauma, and treating the inflammation and pruritus will improve therapeutic results.