Psoriasis: Pathophysiology & Management
Psoriasis is a chronic, immune-mediated, hyperproliferative skin disease characterized by T-cell activation and keratinocyte proliferation. Plaque psoriasis is the most common form.
Key Diagnostic Signs
- Auspitz Sign: Pinpoint bleeding when a scale is removed (due to thinning of the suprapapillary epidermis over dilated dermal capillaries).
- Koebner Phenomenon: Development of lesions at sites of mechanical trauma.
Treatment Hierarchy
| Line | Therapy | Indications |
|---|---|---|
| First-Line | Topical corticosteroids, Vitamin D analogues (Calcipotriene) | Localized/Mild disease. |
| Second-Line | Phototherapy (NB-UVB), Methotrexate, Acitretin | Moderate disease. |
| Third-Line | Biologics (TNF-alpha, IL-17, IL-23 inhibitors) | Severe or refractory disease. |
High-Yield Exam Pearl:
- Systemic Steroid Warning: Never use oral corticosteroids to treat psoriasis, as they can trigger a severe Pustular Psoriasis flare upon withdrawal.
- Comorbidity: Always screen for Psoriatic Arthritis, which can lead to permanent joint damage.