Psoriasis Flashcards
Describe psoriasis
Chronic, genetically determined, immune-mediated, inflammatory skin condition
What is psoriasis usually characterised by?
Well-defined, red, scaly plaques
Name the 8 types of psoriasis
Chronic plaque Flexural Acute guttate Scalp Palmoplantar Nail Pustular Erythrodermic
What is the most common type of psoriasis?
Chronic plaque
What are the 2 unstable forms of psoriasis?
Pustular
Erythrodermic
What is psoriasis caused by (pathophysiology)?
Overactivity of the immune system
Epidermal infiltration by activated T cells and excessive production of what leads to psoriasis?
TH1 cytokines (esp TNF-alpha - linked to flares)
Give the pathophysiological causes each for the erythema, and the plaques + scaling?
Erythema = vascular proliferation; capillary angiogenesis
Plaques + scaling = increased cell turnover
What are the categories for causes/triggers of psoriasis?
Genetics Environmental (stress) Infection Drugs Trauma Sunlight (~10% it worsens; rest it helps) Cigs/alcohol HIV
What types of infection can trigger psoriasis?
Strep
Candida
What drugs can trigger psoriasis?
Lithium ACEI Beta-blockers NSAIDs Steroid withdrawal
What is the koebner phenomenon?
Development/spread of patches of psoriasis as triggered by trauma (cut, bruise, burn etc)
What is the usual rate of skin cell turnover vs rate in psoriasis?
4-5 weeks
3-5 days
Is there a familial component to the development of psoriasis?
Yeah
1 parent = 14%; both parents = 41%
Name some of the genes (3) thought to be associated with psoriasis?
HLA (human leukocyte antigens) Cw6, B13, B17
What are 4 terms that describe the basic histology of psoriasis? Define them?
- Hyperkeratosis = thickening of stratum corneum
- Parakeratosis = keratinocytes with nuclei in stratum corneum
- Hypogranulosis = nogranular layer
- Psoriasiform hyperplasia = acanthosis (thickening of squamous cell) with elongated rete ridges
What are the neutrophils in stratum corneum in psoriasis histology called?
Munro’s microabscesses
What is the appearance of capillaries in psoriasis histology?
Dilated
What percentage of cases of psoriasis is chronic plaque?
90%
What complications can occur in severe chronic plaque psoriasis?
Cardiovascular health impacts; psycho-social impacts
How is chronic plaque commonly managed?
Topical treatments in primary care setting
How is guttate psoriasis usually developed?
Post-viral; usually self-limiting
What does guttate respond well to?
Phototherapy
What can guttate develop into?
Chronic plaque