Psoriasis Flashcards
What drugs can trigger psoriasis?
- Antimalarials
- Lithium
- B blockers
- Indomethacin
- Mepacrine
- ACE inhibitors
- Alcohol
- Topical drugs
- Overuse and sudden withdrawal of some oral corticosteroids
What is Kobners phenomenon?
- Traumatised skin resulting in a psoriatic event at the site of injury
- Cytokines released —> activate T cells
- T cells —> more cytokines, keratinocytes and inflammation
What is plaque psoriasis?
Start as small papules that then grow and unite to form a plaque
What does plaque psoriasis look like?
Classic silvery white scaly appearance
What are the major biological abnormalities of plaque psoriasis?
- Hyperproliferation of the epidermis
- Abnormal differentiation of keratinocytes
- Infiltration of the dermis and epidermis with activated T lymphocytes and neutrophils
- Stimulation of the cutaneous vasculature
What does guttate psoriasis like?
Initially start of as pink papules that become scaly, arises rapidly and responds well to treatment
When does guttate psoriasis usually occur?
After a streptococcal throat infection - possibly superantigen stimulation of the IS
What is erythrodermic psoriasis?
A severe variant that is widespread with massive protein loss, problems maintaining core body temperature and excessive fluid losses - requires aggressive treatment in hospital
What are the complications of erythrodermic psoriasis?
Pustulosis, arthropathy, staphylococcal skin infection and growth retardation
What is pustular psoriasis?
A severe form that causes superficial pustulation of the lesions often on the palms and soles
May be widespread - associated with fever and malaise, fluid and electrolyte disturbances and infection
High relapse rate - can be fatal - hospitalised
What are the main changes to nails in nail psoriasis?
- Pitting
- Oncholysis - selecting nail from nail bed
- Accumulation of subungual debris
- Colour changes
More often finger than toe nails
What is psoriatic arthritis?
In the peripheral interphalangael joints - RF not elevated - difficult to distinguish from rheumatoid arthritis
Associated with cutaneous changes - nail and scalp
What is inverse/flexural psoriasis?
Smooth inflamed lesions mostly in creases or folds - minimal or absent scaling
Perinanal skin in children and beneath breast in women
What are emollients?
Bath oils, soap substitutes and skin creams that moisturise, lubricate and soothe dry flaky skin by forming an occlusive film
To moisturise - apply liberally all over body tid
Psoriatic plaque - pretreatment
Contact dermatitis and foliculitis - ADR’s
Where is dithranol from?
Brazilian tree - Andira araroba
What does dithranol do?
- Slows cell proliferation
- Decrease inflammation
Very effective with no systemic S/E
How do you use dithranol?
- 0.05 - 0.1% starting concentration applied each night at bedtime
- Rinse off each morning - coat skin with emollient
- Increase dose after a few days
- Little increase efficacy after 5%
What are the problems with dithranol?
- Staining
- Inflammation and irritation of non psoriatic skin
- Short treatment
- 0.1% for 5-20 mins
- 1% over 5 mins - Not as effective as calcipotriol in clearing lesions
What is coal tar?
White soft or yellow soft paraffin base available in lotions, gels or shampoos
5% most effective
What are the problems with coal tar?
- Smelly, messy and stains clothing
- Irritation - can cause contact dermatitis
- Phototoxic response
- Don’t apply over a large area - use on well separated small lesions
How are corticosteroids applied?
Applied directly to lesion - goal is to increase time of remission
May make a lesion disappear but may return after discontinuation - taper strength
What do you use for plaque psoriasis?
High potency topical steroid bd until control
What are the S/E’s of corticosteroids?
- Skin atrophy - thinning of skin after 3-14 days
- Increase in fine hair growth
- Hypopigmentation
- Allergic contact dermatitis
- Systemic absorption - adrenal suppression
What is an example of a vitamin D analogue?
Calcipotriol
- 50 micrograms/gram ointment
- 50 micrograms/gram scalp lotion
Max weekly cumulative dose = 5mg ie. 100g or 100ml - use once or twice a day
- notice effect week 2
- max effect - weeks 6 to 8
- flare up if used intermittently
