Overview
Definition
A chronic, immune-mediated inflammatory skin disease characterized by rapid hyperproliferation of keratinocytes.
Epidemiology
Affects 2-3% of the population. Bimodal onset (ages 20-30 and 50-60).
Etiology & Risk Factors
- Autoimmune dysfunction primarily driven by T-cells and cytokines (TNF-alpha, IL-17, IL-23). Strong genetic component (HLA-Cw6).
Clinical Symptoms
- Well-demarcated, erythematous plaques covered with silvery-white scales
- Commonly found on extensor surfaces (elbows, knees), scalp, and gluteal cleft
- Auspitz sign: Pinpoint bleeding when a scale is peeled off
- Nail involvement: Pitting, oil spots, onycholysis
- Pruritus (itching)
Clinical Approach
Diagnosis
- Clinical diagnosis based on classic appearance
- Skin biopsy (rarely needed): Shows epidermal hyperplasia (acanthosis), retained nuclei in the stratum corneum (parakeratosis), and Munro microabscesses (neutrophils in the stratum corneum)
Management
- Mild/Localized: High-potency topical Corticosteroids + Vitamin D analogs (Calcipotriene)
- Moderate/Severe: Phototherapy (UVB)
- Systemic/Refractory: Biologics targeting TNF-alpha (Adalimumab), IL-17 (Secukinumab), or IL-23 (Ustekinumab)
- Methotrexate for severe disease or psoriatic arthritis
Complications
- Psoriatic Arthritis (occurs in up to 30% of patients)
- Metabolic syndrome and increased cardiovascular risk
- Psychosocial distress and depression