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Psoriasis. Definition. Psoriasis Chronic, inflammatory disease of the skin characterized by altered epidermal growth and differentiation with multiple vascular and immunologic abnormalities Still of unknown etiology. Pathophysiology. Initial Lesions. Developing Lesion.
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Definition • Psoriasis • Chronic, inflammatory disease of the skin characterized by altered epidermal growth and differentiation with multiple vascular and immunologic abnormalities • Still of unknown etiology
Pathophysiology Initial Lesions Developing Lesion Increased edema and mononuclear cells in the upper dermis ~50% increase in epidermal thickness Increase in metabolic activity in the epidermis Mast cells, macrophages, T-cells and dendritic cells Slightly dilated venules in upper dermis w/ mononuclear inflitrate Parakeratosis, capillary elongation, rete ridges, lymphocyte, macrophage infiltration “marginal zone” Thickening of epidermis into a band-like pattern
Pathophysiology Mature Lesion Involves various immune cells; e.g.: T-cells – specifically, CD4 and CD8+ cells which are rich in TNF-gamma. This indicates Th1 polarization Dendritic cells – plays a central but still unidentified role Macrophages – thought to fenestrate the epidermal basement membrane and also produces TNF-a Involves various cytokines and chemokines which show a polarization towards Th1 reponse; e.g. TNF-a, IFN-gamma – promotes keratinocyte proliferation Elongated rete ridges w/ thinned out epidermis on top. 100% basal layer mitotic activity Increased infiltration by lymphocytes, macrophages, dendritic cells, mast cells
Co-morbidity • Associated with an increased risk for obesity, metabolic syndrome and insulin resistance • Increased risk for lymphoma but only for Hodgkin’s and cutaneous T-cell types • No significant increase in risk for non-Hodgkin’s lymphomas