Psoriasis

Introduction

Psoriasis is a chronic inflammatory disease characterized by recurrent exacerbations and remissions of thickened, erythematous, and scaling plaques.

CLINICAL PRESENTATION

• Plaque psoriasis (psoriasis vulgaris) is seen in ~90% of psoriasis patients. Lesions are erythematous, red-violet in color, at least 0.5 cm in diameter, well demarcated, and typically covered with silver flaking scales. They may appear as single lesions at predisposed areas (e.g., knees and elbows) or generalized over a wide body surface area (BSA).
• Pruritus may be severe and require treatment to minimize excoriations from frequent scratching. Lesions may be physically debilitating or socially isolating.
• Psoriatic arthritis involves both psoriatic lesions and inflammatory arthritis-like symptoms. Distal interphalangeal joints and adjacent nails are most commonly involved, but knees, elbows, wrists, and ankles may be affected

DIAGNOSIS

Diagnosis is based on physical examination findings of characteristic lesions. Skin biopsies are not diagnostic of psoriasis.

• Classification of psoriasis as mild, moderate, or severe is based on BSA and Psoriasis Area and Severity Index (PASI) measurements. A 2011 European classification system defines severity of plaque psoriasis as either mild or moderate-to-severe.

TREATMENT

Goals of Treatment: Minimize or eliminate skin lesions, alleviate pruritus, reduce frequency of flare-ups, treat comorbid conditions, avoid adverse treatment effects, provide cost-effective treatment, provide appropriate counseling (e.g., stress reduction), and maintain or improve quality of life.

Calcipotriene 0.005% cream, ointment, or solution is applied one or two times daily (no more than 100 g/wk).

Tazarotene (Tazorac) is a topical retinoid that normalizes keratinocyte differentiation, diminishes keratinocyte hyperproliferation, and clears the inflammatory infiltrate in psoriatic plaques. It is available as a 0.05% or 0.1% gel and cream and is applied once daily (usually in the evening)

Salicylic acid has keratolytic properties and has been used in shampoos or bath oils for scalp psoriasis.

Cyclosporine usual dose is between 2.5 and 5 mg/kg/day given in two divided doses. After inducing remission, maintenance therapy using low doses (1.25–3 mg/ kg/day) may prevent relapse.

Phototherapy consists of nonionizing electromagnetic radiation, either ultraviolet A (UVA) or ultraviolet B (UVB), as light therapy for psoriatic lesions. UVB is given alone as either broadband or narrowband (NB-UVB).

Methotrexate has anti-inflammatory effects due to its effects on T-cell gene expression and also has cytostatic effects. The starting dose is 7.5 to 15 mg once weekly, increased incrementally by 2.5 mg every 2 to 4 weeks until response; maximal doses are 25 mg weekly.