Psoriasis Flashcards
Types
Vulgaris (Chronic Plaque), most common
Guttate
Erythrodermic
Genetics
Autoimmune condition
Has a strong genetic component - not fully understood
Triggers/causes
Variety of potential causes:
Environmental factors
Stress
Drugs - lithium, antimalarials, B-blockers
Commonly affected areas
Skin Extensor surfaces - outside of elbows Nails Joints Scalp
Immunology
Chronic inflammatory dermatosis
T cell mediated disorder driven by unidentified antigens.
APCs (dendritic cells) are activated
Up-regulation of Th1 and Th17 cells
T cells secrete IL17A/17F/22 which stimulates keratinocyte proliferation
Keratinocytes produce AMPs that can directly kill pathogens (found in high levels in psoriatic patients)
Pathology
Epidermal hyperplasia - rapid epidermal turnover
Dead skin cells build up (acanthosis) and form plaques instead of shedding from skin
Granular layer often absent
Morphology of plaques
Well demarcated Flakey, silver scaly Pink/red Inflammation Symmetrically distributed
Symptoms
Itchy
Painful
Koebner phenomenon
Psoriasis plaques develop in an area of skin trauma (i.e. scar)
Guttate psoriasis presentation
Rain drop appearance over trunk and limbs
Explosive eruption of small oval/circular plaques
Occurs around 2 weeks after a streptococcal sore throat
Erythrodermic psoriasis presentation
Widespread, affects over 90% of the body
Most severe type
Nail changes
Pitting of nail plate
Onycholysis - distal separation of nail
Subungal hyperkeratosis
Co-morbidities
Crohn’s disease
Uveitis
Metabolic syndrome
Management - topical
Emollients - hydrate skin Vit D analogue - eg calcipotriol Coal tar - messy, smelly Keratolytic Topical steroid Dithranol - stains skin and clothing
Management
Topical therapy
Phototherapy (UVB and PUVA)
Systemic agents (methotrexate, immunosuppressives)
Targeted biologic agents
