Psoriasis

Psoriasis is a chronic immune-mediated inflammatory skin disorder with a strong genetic predisposition. It is characterized by hyperproliferation of keratinocytes, leading to thickened, scaly plaques on the skin.

The disease follows a chronic relapsing and remitting course and may significantly affect quality of life. It is not contagious.

Psoriasis may also involve:

• Nails

• Joints (psoriatic arthritis)

• Scalp

Epidemiology

• Affects 1–3% of the global population

• Can occur at any age

• Peaks at 20–30 years and 50–60 years

• Family history common

Etiology and Risk Factors

Psoriasis is multifactorial:

Genetic predisposition

• Strong familial association

Triggering factors

• Stress

• Alcohol

• Smoking

• Infections (especially streptococcal throat infection)

• Trauma to skin (Koebner phenomenon)

• Drugs (beta-blockers, lithium, antimalarials)

• Deficiencies of vitamin B12 or folate

Pathophysiology

• Immune system dysregulation involving T-cells

• Overproduction of inflammatory cytokines (TNF-alpha, IL-17, IL-23)

• Rapid epidermal turnover (3–5 days instead of 28 days)

• Accumulation of immature keratinocytes → scaling plaques

Clinical Types

Plaque Psoriasis (most common)

• Thick silvery white scaly plaques

• Extensor surfaces and scalp

Guttate Psoriasis

• Small drop-like lesions

• Often after streptococcal infection

Pustular Psoriasis

• Sterile pustules

Erythrodermic Psoriasis

• Generalized redness and scaling

• Medical emergency

Nail Psoriasis

• Pitting

• Onycholysis

• Subungual hyperkeratosis

Psoriatic Arthritis

• Joint pain and stiffness

Signs & Symptoms

• Thick, silvery white scaly plaques

• Well-demarcated erythematous base

• Common sites:

  • Scalp

  • Sacral region

  • Extensor surfaces (elbows, knees)

• Symmetrical distribution

• Chronic relapsing course

• Itching (variable severity)

Diagnostic Criteria

Clinical diagnosis based on:

• Well-demarcated erythematous plaques

• Silvery white scales

• Symmetrical distribution

• Chronic relapsing pattern

Supportive clinical signs:

• Auspitz sign (pinpoint bleeding when scales removed)

• Koebner phenomenon

Always exclude precipitating factors such as alcohol use, infections, stress, and vitamin deficiencies.

Investigations

Usually clinical diagnosis.

If needed:

• Skin biopsy (acanthosis, parakeratosis)

• Full blood count

• ESR or CRP (if arthritis suspected)

• Vitamin B12 and folate levels

• Throat swab (guttate type)

• Liver and renal function tests before systemic therapy

Treatment

Treatment depends on severity and extent.

Non-Pharmacological Treatment

• Sun exposure to lesions (30–60 minutes daily)

• Avoid alcohol and smoking

• Stress reduction

• Weight control

• Regular moisturization

• Avoid skin trauma

Pharmacological Treatment

Topical Therapy (Mild to Moderate Disease)

Morning:

• Crude Coal Tar 5% in Vaseline

Night:

• Salicylic acid 5% in Vaseline (for de-scaling)

Evening:

• Betamethasone ointment 0.025%

Alternative Regimen

• Dithranol 0.1% once daily

Moderate to Severe Disease

If poor response, refer to higher-level facility for:

• Methotrexate

• Cyclosporine

• Azathioprine

• Phototherapy

• Biologic therapy (specialist setting)

Systemic corticosteroids are discouraged due to severe rebound flare.

Complications

• Psoriatic arthritis

• Erythroderma

• Nail deformity

• Cardiovascular risk increase

• Depression and anxiety

Prognosis

• Chronic lifelong condition

• Periods of remission and relapse

• Early treatment improves outcomes

Prevention

• Avoid triggering factors

• Treat infections early

• Maintain healthy lifestyle

• Adherence to treatment

• Regular follow-up