Psoriasis

Epidemiology


Etiology


Pathophysiology


Clinical features


Cutaneous lesions

Nail involvement

Diagnostics


Skin biopsy

Differential diagnostics


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vs Lichen planus Pasted image 20240228105319.png

Psoriasis vs Lichen planus

  • Immune Mechanism:
    • Lichen Planus primarily involves CD8+ T cells targeting basal keratinocytes, creating a band-like lymphocytic infiltrate at the dermo-epidermal junction and interface dermatitis
    • Psoriasis is driven by Th17/Th1 cells and involves complex cytokine cascades (IL-17, IL-22, TNF-α), affecting the entire epidermis and leading to neutrophil recruitment
  • Keratinocyte Response:
    • Lichen Planus shows normal to slow keratinocyte turnover, allowing time for proper differentiation, resulting in hypergranulosis (increased keratohyalin granules)
      • Because of immune stress?
    • Psoriasis exhibits extremely rapid keratinocyte turnover (3-5 days vs normal 28-30 days), preventing proper differentiation, leading to loss of granular layer and parakeratosis

Treatment