Psoriasis Flashcards
What is the aetiology and epidemiology of psoriasis?
Common, chronic, scaly rash that affect people of all ages (~2% of population)
Tends to run in families, also influenced by environmental factor.
Not contagious and not due to allergy.
Most common ages for psoriasis: late teens, 2nd, 3rd and 6th decades.
5% of people with psoriasis will develop psoriatic arthritis (can be very debilitating)
Exact cause is not fully understood.
Immune system is involved and appears to be overactive causing inflammation. Also causes growth of extra blood vessels within the skin (red colour)and increased in skin cells turnover from 28 days to 4 days (scaling and thickening of skin)
What are the precipitating factors for psoriasis?
- genetic
- stress
- infection
- streptococcal tonsilitis (causes guttate psoriasis)
- Candida infection (causes flexural psoriasis)
- Malassezia furfur yeast (causes sebopsoriasis)
- injury
- hormones
- infection
- alcohol and smoking
- UV light usually beneficial except for photosensitive psoriasis)
What is the pathology for psoriasis?
Thickened epidermis with keratinocytes retaining their nuclei.
No granular layer with keratin building up loosely at horny layer
Rete ridges are elongated with polymorphs infiltrating up into stratum corneum forming micro abscess.
How would psoriasis present?
Red, scaly rash with well-defined edges
Often symmetrical affecting both sides of the body
Scale often silvery white
When psoriasis clears up, may leave post-inflammatory hyperpigmentation or hypopigmentation (does not cause true scarring)
What are the different types of psoriasis?
- Chronic plaque psoriasis
- Guttate psoriasis
- Pustular psoriasis
- Sebopsoriasis
- Palmoplantar psoriasis
- Nail psoriasis
- Photosensitive psoriasis
- Flexural psoriasis
- Scalp psoriasis
- Erythrodermis psoriasis
- Psoriatic arthritis
What are the topical management choices for psoriasis?
- Vitamin D analogue (calcipotriol)
- clean, does not dye the skin or cause skin atrophy, inhibit cell proliferation, stimulate keratinocytes differentiation. May irritate. If dose too high may cause hypercalcaemia. - Topical steroids
- clean, non-irritant and easy to use. Can cause skin atrophy and precipitation upon withdrawal in unstable psoriasis. Treatment of choice for psoriasis in face (not strong ones), flexures and genitalia. Also in stubbord plaque psoriasis in scalp, hands and feet. - Tar preparation (alphosyl, carbo-dome)
- used for chronic guttate psoriasis. Combine with UVB. Inhibit DNA synthesis. Messy and smelly. - Dithranol (Anthralian)
- Anti-mitotic and is irritant to normal skin. Stains skin and hair etc purple/brown. Cannot be used on face and genitalia. Unaffected skin to be protected with white paraffin. - Retinoids
- for chronic psoriasis plaques as an alternative to topical steroids - Keratolytics (salicylic acids)
- used on palms, soles and scalps in combination with tar shampoos
*Vitamin D analogue (calcipotriol) Topical steroids Tar preparation (alphosyl, carbo-dome) Dithranol (Anthralian) Retinoids Keratolytics (Salicylic acid)
What are the systemic management choices for psoriasis?
- Methotrexate
- Folate antagonist. Anti inflammatory and immune modulatory effects. Normal marrow, liver and kidney function must be established. Improvement within 2-4 weeks. No suitable for alcoholic liver disease and acute infection. SEs include liver cirrhosis, liver fibrosis and nausea + teratogenic. - Cyclosporin
Immunosuppressant. Inhibits T-lymphocytes activation and IL-2 production. Nephrotoxic. Monitor BP and kidney f(x). Risk of skin ca and lymphoma - avoid UV treatment. - Retinoid (Neotigasone)
Vitamin A derivative, particularly effective for pustular psoriasis and hyperkeratotic plaque. Can be used with topical therapies but better with low dose of UV. SEs include dry skin, peely skin. Hyperostosis, liver probs, hyperlipidaemia. Teratogenic.
- Methothrexate
Cyclosporin
Retinoids
(MCR)
