Psoriasis: A Common Skin Condition

1. Introduction

Psoriasis is a chronic, non-contagious skin condition characterized by excessive skin cell growth, leading to the formation of red, scaly patches on the skin. The condition can affect people of all ages, but it is most common in individuals between the ages of 15 and 35, and in men.

2. Symptoms

Skin lesions:

• Location: Commonly appear in areas of skin that are subjected to pressure (e.g., elbows, knees), extensor surfaces of limbs, scalp, back, chest, face, groin, and buttocks.
• Morphology: Red patches with well-defined borders, rough surface, covered with white scales, feeling dry and firm to the touch.
• Characteristics:
  • Symmetry: Patches usually appear symmetrically on both sides of the body.
  • Positive Auspitz Sign: When gently pressed on the affected area, the redness fades, but returns to its original color after releasing the pressure.

Scales:

• Characteristics: Dry, thick, overlapping, opaque white-pearlescent, easily shed.
• Positive Brocq Phenomenon: When gently scraping the scales, they come off easily revealing a red underlying layer. Further scraping causes bleeding with the appearance of “blood dew drops” (Auspitz sign).

Nail involvement (fingernails, toenails):

• Morphology:
  • Nail pitting: The nail surface has small depressions resembling the holes of a sewing needle.
  • Onycholysis: The free edge of the nail separates from the nail bed.
  • Subungual hyperkeratosis: Small bumps develop under the nail.
  • Oil drop sign: Small oil drops appear under the nail.
  • Nail dystrophy: The nail separates from the nail bed.

Joint involvement:

• Psoriatic arthritis:
  • Symptoms: Joint pain, limited mobility, swollen joints, particularly in the finger, toe, wrist, and ankle joints.
  • Complications: Can lead to destructive joint disease (arthropathy) if not treated promptly.

Size of lesions:

• Guttate: < 1 cm
• Coin-shaped: 1 – 3 cm
• Plaque: > 5 cm

Pustular psoriasis:

• Symptoms: Small pus-filled pimples, pinhead-sized, white, located under the scaly layer.
• Examination: Bacteria are not found in these pustules.

Erythrodermic psoriasis:

• Symptoms: A severe complication caused by excessive corticosteroid use.
• Presentation: Widespread erythema, heavy scaling, severe itching.

3. Causes

• Genetics: The HLA-B17 gene plays a significant role in the development of psoriasis, especially in the guttate and erythrodermic forms.
• Immune system: The immune system overreacts, attacking healthy skin cells, causing excessive skin cell growth.
• Environment:
  • Infections: Group A streptococcal infections can trigger psoriasis flare-ups.
  • Stress: Psychological stress can exacerbate the condition.
  • Medications: Some medications, such as lithium, beta-blockers, and antihypertensive drugs, can trigger or worsen psoriasis.
  • Diet: A diet rich in sweets and animal fats may increase the risk of developing psoriasis.
  • Climate: Sudden hot or cold weather can also exacerbate the condition.

4. Diagnosis

• Clinical:
  • Based on typical clinical presentations, especially the positive Brocq phenomenon and Auspitz sign.
• Investigations:
  • Skin biopsy: Confirms the diagnosis and rules out other skin conditions.
  • Blood tests: Assess inflammation, liver and kidney function, etc.
  • Genetic testing: Identifies the HLA-B17 gene.

5. Differential diagnosis

• Other red-scale skin conditions:
  • Pityriasis rosea: No blood dew drops. Scraping the scales shows a “glue-like” appearance.
  • Fungal infections: May cause intense itching and spread.
• Systemic lupus erythematosus:
  • Scales are difficult to remove, skin atrophy, often with fatigue, muscle and joint pain.
• Seborrheic dermatitis:
  • Moist scales, usually found on the scalp, nasolabial folds, the area in front of the sternum, and the shoulders.
• Secondary syphilis:
  • Usually presents as pink papules, without scales.

6. Treatment

• Treatment goals:
  • Reduce inflammation, itching, and scaling.
  • Control the condition and prevent recurrence.
• Topical treatment:
  • Topical medications:
    • Keratolytics: Salicylic acid, vitamin A cream, zinc oxide, etc.
    • Antioxidants: Calcipotriol (vitamin D3 derivative), Daivonex, Dovonex.
    • Anti-inflammatories: Corticosteroids (creams, ointments).
  • Phototherapy:
    • UVA: 3 times a week.
    • UVB: Narrowband UVB, PUVA (Psoralen + UVA).
• Systemic treatment:
  • Oral medications:
    • Retinoids:

      Note: Can cause side effects such as dry eyes, hair loss, fatty liver.

    • Methotrexate:

      Note: Can be toxic to the liver, affect the bone marrow, requires regular monitoring of liver and kidney function.

    • Cyclosporine A:

      Note: Can cause high blood pressure, reduced kidney function, and infections.

    • Corticosteroids:

      Note: Only used orally for severe cases with life-threatening complications. Topical corticosteroids are preferred over oral corticosteroids.

  • Biologics:
    • Indications: For severe cases, extensive plaques, unresponsive to other treatments, pustular psoriasis, psoriatic arthritis.
    • Drug groups:
      • Interleukin inhibitors: (IL-17, IL-23)
      • TNF-α antagonists: (Etanercept, Infliximab, Adalimumab…)
• Supportive treatment:
  • Diet: Limit sweets, animal fats, and consume plenty of fruits and vegetables.
  • Exercise: Maintain a healthy lifestyle, exercise regularly.
  • Stress management: Try to reduce stress, practice yoga, meditation, etc.
  • Skin care: Bath with warm water, use mild soaps, and moisturize regularly.
  • Control risk factors:
    • Infections: Treat infections promptly.
    • Stress: Find ways to relieve stress and avoid anxiety.
    • Medications: Avoid medications that can trigger or worsen psoriasis.

7. Complications

• Lichenification: Red, itchy, scaling patches, often develop in individuals with long-standing psoriasis.
• Skin cancer: Higher risk of skin cancer in individuals with psoriasis, especially those who have used UVB phototherapy for long periods.
• Erythroderma: Caused by excessive corticosteroid use.
• Psoriatic arthritis: Leads to joint deformity and limited mobility.
• Munro’s microabscess: Bacterial infection of psoriatic lesions.

8. Notes

• Psoriasis is not contagious.
• Psoriasis treatment is a long-term process that requires patience and adherence to doctor’s instructions.
• Avoid self-treating with medications, especially corticosteroids, and follow your doctor’s prescription.
• Be aware of potential side effects of medications, and report any adverse reactions to your doctor.
• Monitor your condition regularly, and notify your doctor if it worsens.

9. Classification

• Guttate psoriasis:
  • Numerous small, pink drops with thin scales.
  • Common in children and young adults.
  • Associated with group A streptococcal infections.
  • Associated gene: HLA-B17.
• Plaque psoriasis:
  • Red patches with thick, tightly adhering scales.
  • The most common type.
• Coin-shaped psoriasis:
  • Small, round, pink patches with thin scales.
• Erythrodermic psoriasis:
  • Widespread erythema, heavy scaling, and severe itching.
  • Associated gene: HLA-B17.
• Psoriatic arthritis:
  • Presents with joint inflammation, pain, and limited mobility.
  • Associated gene: HLA-B27.
• Pustular psoriasis:
  • Small, white pus-filled pimples located under the scaly layer.
  • Associated genes: HLA-B8, DR3, BW35, CW7.

10. PASI (Psoriasis Area and Severity Index) – Severity index for psoriasis

• Assessment factors:
  • Erythema (redness): 0 – 4
  • Scaling (thickness): 0 – 4
  • Thickness: 0 – 4
  • Surface area: 0 – 6
• Classification:
  • Mild: PASI < 10
  • Moderate: PASI 10 – 20
  • Severe: PASI > 20

11. Research

• IL-17, IL-23: Studies have demonstrated the important role of IL-17 and IL-23 cytokines in the development of psoriasis.
• Genes:
  • HLA-B17: Associated with guttate and erythrodermic psoriasis.
  • HLA-B27: Associated with psoriatic arthritis.
  • HLA-B8, DR3, BW35, CW7: Associated with pustular psoriasis.

12. Conclusion

Psoriasis is a chronic, non-contagious skin disease that negatively impacts the quality of life of affected individuals. Prompt diagnosis and treatment, adherence to doctor’s instructions, and ongoing monitoring are crucial to control the condition and prevent recurrence.