psoriasis

Question 1

what is psoriases?

Answer 1

Chronic, genetically determined, immune-mediated, inflammatory skin condition, characterised by typically well defined, scaly plaques. It can also involve nails, hair and joints

Question 2

What is the epidemiology of psoriases?

Answer 2

3% of uk pop. M=F
peak incidences- 20s, 50s
uncommon in Far East population, native Americans, west africans.

many have family history.

Question 3

Complications?

Answer 3

5% develop psoriatic arthritis
psychosocial implications
systemic disease, link to metabolic syndrome and CV disease

Question 4

How does it present?

Answer 4

red scaly plaques
often symmetrical distribution

chronic plaque
flexural
acute guttate
scalp
palmoplanter
nail
pustular
erythrodermic

Question 5

What causes it?

Answer 5

overactivity of the immune system
excessive production of the TH1 cytokine inc TNF-alpha
-vascular proliferation (erythema), increase cell turnover (plaques and scaling)

Question 6

RF?

Answer 6

• genetics
• environmental
  infection: strep, candida
• drugs- lithium, beta blocker, NSAIDs, steroid withdrawal
• Trauma- kobner phenomenon (spread with trauma
• sunlight

Question 7

What are the 3 main pathogenesis?

Answer 7

• Epidermal imnfiltartion by activated T cells
• Genetics
• Precipitants

Question 8

explain epidermal infiltration by T cells?

Answer 8

• there is increase epidermal cell proliferation and turnover- cell cycle reduced from 28 days to 3-5 days, capillary angiogenesis.
• -exsessive production of TH1 cytokines esp TBF-alpha linked to flares

Question 9

explain the genetics linked to to pathogenesis?

Answer 9

• Familuy history
• 1 parent has psoriases= 14% of child developing
• both parents have = 41% chance

Question 10

what genes have a link to psoriases?

Answer 10

-HLA Cw6, B13, B17

Question 11

factors that make psoriasis worse? (precipitant factors)

Answer 11

trauma
infection
drugs- beta blockers, lithium
sunlight
stress
cigarettes
alcohol
HIV

Question 12

Histology in psoriases?

Answer 12

Hyperkeratosis (thickening of stratum corneum) with parakeratosis (keratinocytes with nuclei in stratum corneum)
Neutrophils in stratum corneum (munro’s microabcesses)
Hypogranulosis: no granular layer (needed for barrier function)
Psoriasiform hyperplasia: Acanthosis (thickening of squamous cell layer) with elongated rete ridges

Dilated dermal capillaries
Perivascular lymphohistiocytic infiltrate; T cell infiltration