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Psoriasis Vulgaris

L. Guenther, MD, FRCPC
Professor of Dermatology, University of Western Ontario, London, Canada

Psoriasis Vulgaris

Psoriasis vulgaris is an autoimmune disease in which activated T-cells express TH1 cytokines. It is manifested by cellular hyperproliferation, lack of differentiation and inflammation. Approximately 1/3 of patients have a relative with psoriasis, and 85% have a link with the HLA-Cw6 gene.

  • Red, scaly plaques that are often itchy and are commonly located on the elbows,
  • knees, lumbo-sacral area, and scalp, although any part of the skin may be affected
  • Chronic, but may have periods of remission
  • May have concomitant nail changes (pitting, onycholysis, oil drop changes,
  • subungual hyperkeratosis, nail plate thickening)
  • May have psoriatic arthritis (in ~30% of population).

Impact on the Sufferer

Psoriasis has a greater mental and physical impact than myocardial infarction, hypertension, diabetes mellitus, arthritis, and cancer; only depression had a greater mental impact, and congestive heart failure a greater physical impact.[Rapp SR, et al. J Am Acad Dermatol 41:401-7 (1999).] A 1998 US National Psoriasis Foundation survey showed that 40% of individuals with psoriasis had trouble receiving service in establishments such as hair salons, pools and health clubs. In the 18-34 year age group:

  • 81% felt embarrassed
  • 75% felt unattractive
  • 54% suffered from depression
  • 10% had contemplated suicide.

Treatment: Self-help and Medical Treatments

Treatment depends on:

  • the sites of involvement
  • severity
  • response to previous treatment
  • other medical conditions
  • concomitant medications
  • proximity to medical resources (e.g., phototherapy units)
  • patient preference.

1. Patient Self-help

Avoid trauma (e.g., a scrape). In ~1/3 of patients injury to the skin can induce psoriasis in the area of injury (called the “Koebner phenomenon”).

  • Clean with mild cleansers and tepid water.
  • Moisturizers minimize scaling, painful fissuring and itching. They should be applied immediately after bathing.
  • Salicylic acid is a keratolytic and increases the penetration of topical corticosteroids. It is helpful for thick scaling and on thepalms, soles and scalp.
  • Apply tar bath oils, creams, lotions and ointments once or twice daily. Use is limited by the smell, potential to stain, irritation, and folliculitis.
  • Shampoos containing tar, salicylic acid, zinc pyrithione, ketoconazole and many “dandruff ” shampoos can help with scalp scaliness.
  • Hydrocortisone cream may be helpful for facial and fold psoriasis; however, a stronger topical corticosteroid is usually required elsewhere.
  • Oral antihistamines help with itching. Non-sedating ones should be used during the day and sedating ones at bedtime.

2. Medical Treatment

Avoid Aggravating Medications

In some patients beta-blockers, ACE inhibitors, antimalarials and lithium may aggravate the disease or make it more resistant to treatment.

Topical Agents

These are the most commonly used treatments, either as monotherapy for localized disease, or as adjunctive treatment for moderate-to-severe disease.

Topical Corticosteroids

  • Available in low, medium, high and ultra high potency
  • Use lotions for the scalp, creams and ointments elsewhere, and gels anywhere
  • Use the steroid with the lowest effective potency, particularly on the face and folds
  • Safe for short-term or intermittent long-term treatment
  • Once daily is often as efficacious as twice daily
  • May be able to maintain remission with intermittent use 2-3 times/wk
  • Adverse effects include:
    • atrophy
    • striae
    • telangiectasia
    • contact sensitization
    • tachyphylaxis (lack of effect with continued use)
    • flare upon discontinuation
    • adrenal suppression.

Topical Calcipotriol (Dovonex®)

  • Cream and ointment for trunk and limbs; also a solution for the scalp
  • Use twice daily to obtain control, then once or twice daily to maintain remission
  • May also maintain remission with weekday calcipotriol and weekend superpotent topical corticosteroid (e.g., Ultravate®)
  • Synergistic with potent or superpotent topical corticosteroids, ultraviolet B (UVB) phototherapy, psoralen + ultraviolet A (PUVA) phototherapy, methotrexate, cyclosporine, and acitretin
  • Safe long-term, 100g/wk maximum
  • Adverse effects:
    • irritation (usually mild; rarely results in discontinuation)
    • facial dermatitis.

Topical Dovobet®

  • Contains calcipotriol and betamethasone dipropionate in the same concentrations as Dovonex®‚ and Diprosone®‚ respectively
  • Once daily application
  • ~50% of patients are clear or almost clear after 4 weeks of treatment
  • Faster and more efficacious than its individual components
  • Similar cutaneous adverse events to betamethasone dipropionate; ~ half that of calcipotriol
  • Consider maintaining remission after Dovobet® treatment with either calcipotriol monotherapy or calcipotriol during weekdays and Dovobet® on the weekends.

Topical Tazarotene (Tazorac®)

  • Selective retinoid
  • Commonly used once daily with a mid- or high-potency steroid once daily
  • Improvement may be maintained with Mon/Wed/Fri tazarotene and Tues/Thurs clobetasol ointment
  • Synergistic with topical cortosteroids, calcipotriol, phototherapy (UVB, PUVA)
  • Contraindicated in pregnancy
  • Irritation limits use.

Topical Calcineurin Inhibitors

  • Topical pimecrolimus (Elidel®‚ 1% cream) and tacrolimus (Protopic®‚ 0.03% and 0.1% ointment) twice daily for facial and intertriginous psoriasis
  • Do not cause atrophy
  • May cause burning or stinging, particularly initially.

Intralesional Corticosteroids

  • Small plaques may be injected with triamcinolone 10mg/cc diluted with saline or water to 5mg/cc.

Moderate-to-Severe Disease

Psoriasis is considered to be moderate-to-severe if it affects10% or more of the body surface area, OR less than 10% if:

a) plaques are very red, thick, and scaly, or
b) there is a significant impact on quality of life (e.g., functional impairment, marked discomfort) or
c) disease is resistant to topical agents. Phototherapy, traditional systemic agents and biologic agents are used with adjunctive topical agents.

Phototherapy

  • Broad band UVB (290-320nm), Narrow band (311nm) to be given 2-5 times/week or
  • PUVA (UVA: 320-400) to be given 2-3 times/week.

Traditional Systemic Medication

  • Methotrexate 5-25mg once weekly: helps skin and arthritis; may cause bone marrow suppression and hepatoxicity (a liver biopsy should be done after a cumulative dose of 1.5gm)
  • Cyclosporine 2.5-5mg/kg/day: treatment should be limited to 1 year due to risk of nephrotoxicity
  • Acitretin 25mg-50mg/day: often combined with phototherapy; teratogenic, so rarely used in women with childbearing potential (must avoid pregnancy for at least 2-3 years after discontinuation). Adverse effects also include mucocutaneous dryness, lipid elevation, hepatotoxicity, and bony abnormalities.

Biologic Agents

  • Treatments that target specific cells, molecules and receptors
  • Alefacept (Amevive®) is currently the only approved biologic agent in Canada for the treatment of psoriasis
  • Etanercept (Enbrel®) may halt radiographic progression of psoriatic arthritis
  • Studies have also shown efalizumab, infliximab and adalimumab to be efficacious in the treatment of psoriasis.