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
Which type of psoriasis has been shown to have the greatest effect on patients quality of life?
Palmo-plantar
What is a differential diagnosis for scalp psoriasis?
Seborrheic dermatitis
Psoriasis scales are usually thicker/drier and tend to extend more beyond the scalp
Give the 2 pathognomic features of nail psoriasis?
- Pitting
2. Oncholysis
What is a distinctive feature of flexural/inverse psoriasis?
Lack of scales - just red, sharply demarcated plaque often at skin folds e.g. armpits
Describe the appearance of pustular psoriasis
Generalised red, tender patches with multiple small yellow pustules
How would you describe a patient who presented with a long history of chronic plaque, with a recent flareup and generalised erythema of the skin with fine scale along with pyrexia and low BP?
Erythrodermic psoriasis
What is erythrodermic psoriasis also known as?
‘Red Man Syndrome’ - >90% body surface involved
Where should erythrodermic psoriasis be managed?
Hospital
Give 3 differentials for psoriasis
Seborrhoeic dermatitis (esp scalp, face) Lichen planus (check forearm, oral mucosa) Mycosis fungoides (older PT, sudden onset - biopsy)
Give the first line treatment plan for psoriasis
Topical steroids (flexural/genital area) Vit D3 analogues (calcioptriol) +/- steroids Tar creams \+ Emollients (to smooth skin) \+ Salicylic acid (to remove plaques)
Give the 2nd line treatment for psoriasis
Dithranol/Anthralin - slower onset of action and has various side effects e.g. staining of skin/clothes and cant be applied to face/genitals
Give some 3rd line options for psoriasis treatment
- UVB Phototherapy
- Acitretin (teratogenic, impairment of LFTs/lipids)
- Methotrexate (also for joint/nail involvement, improvement in 2-3 months)
- Cyclosporin
- Inpatient Tar (crude coal tar in zinc ointment)
- Biologics - qualifying criteria, cost
- Retinoids, immunosuppressants
What is the treatment plan for ERYTHRODERMIC psoriasis
ADMIT
Fluid balance
Bloods/IV access
Thick greasy ointment emollients
What are the 2 criteria for monitoring of psoriasis
PASI (psoriasis area severity index)
DMQI (dermatology life quality index) - more general
In what percent of psoriasis patients does it progress to arthritis?
5-10%
