– Clinical stages, mild defined as <3 % BSA, moderate 3–10 %, severe >10 %
– Measure of extent of Psoriasis – the PASI (Psoriasis Area and Severity Index), based on redness,
thickness, and scaliness of lesions
– Nail findings include nail pitting, oil spots, onycholysis, thickened nails
– Associated with systemic inflammatory co-morbidities (e.g., increased risk of cardiovascular disease)
– Pathogenesis = T-cell activation with cytokine mediated keratinocyte proliferation (Th1 and Th17), mostly CD8+ T-cells
– Pathology: psoriasiform hyperplasia, parakeratosis, neutrophils in the epidermis (pathognomonic for psoriasis and AGEP) = “Munro’s microabscesses” in stratum corneum, “Spongiform pustule of Kogoj” in stratum spinosum.