Psoriasis
Epidemiology
Affects around 2% of UK population
Occurs equally in men and women
Onset is at any age
Essentially its the opposite to eczema (where there is break-down of skin) since its hyper-proliferation of skin leading to thickened plaques
Peak prevalence in early adulthood
Second peak between 50-60 years
UNCOMMON in children
Risk factors
Also dependent on certain environmental triggers
Family history
Appears to be polygenic
UV light
High alcohol use
Drugs e.g. lithium
Stress
Infection with group A Streptococcus
Pathophysiology
T cell activation results in up regulation of Th1 type T cell cytokines
Psoriasis is a T-lymphocyte driven disorder to unidentified antigen
Upregulation of these cytokines results in increased uncontrolled hyper proliferation of the keratinocytes in the epidermis with an increase in the epidermal cell turnover state
Chronic, inflammatory skin disease due to hyper proliferation of keratinocytes + inflammatory cell infiltration
Clinical presentation & Treatment
Associated with nail changes - pitting and onycholysis (separation of finger nail from nail bed)
Chronic plaque psoriasis
Presentation
Treatment
Scalp involvement is common and is most seen at the hair margin
Thickened epidermis
Well-demarcated disc-shaped, SALMON-PINK SILVERY PLAQUES occur on the exterior surface of the limbs, particularly the elbows and knees
New plaques of psoriasis occur at sites of skin trauma
Most common
Emollients e.g. E45
Topical vitamin D analogues
Inhibit cell proliferation and stimulate keratinocyte differentiation
Topical corticosteroids e.g. hydrocortisone
Topical retinoids e.g. Tazarotene
UV B or Coal Tar
Anti mitotic e.g. dithranol - USE ON LARGE PLAQUES ONLY
For extensive plaques
Phototherapy with UV A
Immunosuppressant e.g. Ciclosporin
Disease modifying anti-rheumatic drug (DMARD)
Inhibits folic acid metabolism thus inhibits DNA replication
Leads to anti-proliferative and anti-inflammatory effect
MUST give FOLIC ACID SUPPLEMENTS 48HRS AFTER TREATMENT
Example - oral methotrexate
Side effect - hepatotoxic
Contraindications
Pregnancy/breast feeding
Hepatic disease/alcoholism
Renal impairment
Active infection
Live vaccines
Flexural psoriasis
Presentation
Treatment
Scaling is ABSENT
Confined to flexures e.g. groin, natal cleft, sub-mammary areas
Well-demarcated red, glazed, non-scaly plaques
Can be mistaken for candida interring - but this will normally show satellite lesions
Tends to occur later in life
1st line
2nd line
Topical mild-moderate corticosteroids e.g. hydrocortisone
Short course to avoid atrophy
Topical vitamin D analogue
Guttate (raindrop-like) psoriasis
Presentation
Treatment
Generalised, concentrating on the trunk, upper arms and legs
An explosive eruption of very small circular or oval plaques appears over the trunk about 2 weeks after a STREP sore throat
Most commonly in children and young adults
Topical mild-moderate corticosteroids
UV B
Coal Tar
Palmoplantar psoriasis
Presentation
Treatment
Thickening of the palms and soles
Keratolytic agents
Potent topical corticosteroids
Emollients
Phototherapy with UV A
Oral retinoid e.g. Acitretin
Vitamin A derivative
Anti-proliferative action
Used alongside phototherapy
Side effects: dry lips, eyes & mucosa, hyperlipidaemia, disturbed liver functions
Tetratogenic thus contraindicated in pregnancy