Psoriasis Flashcards
What is psoriasis?
A common chronic, autoimmune, hyperproliferative disorder
There are red scaly skin plaques seen commonly on extensor surfaces like elbows and knees, and in scalp
Who gets psoriasis?
Both genders are affected equally
Not usual in children
Peak prevalence in early and late adulthood
What is the pathogenesis of psoriasis?
Mediated by T lymphocytes response to an antigen (we don’t know what!)
T cells are activated and trigger an immune response with cytokines
Keratinocyte hyperproliferation
The skin cycle goes much faster than it should
A skin cell goes from the bottom (basal) layer to the top (horny) layer in 4 days rather than 4 weeks
What are some histological appearances of psoriasis?
Acanthosis: thick epidermis
Dilated, tortuous capillaries
T cells in upper dermis
Parakeratosis: retained nuclei
Name the types of psoriasis?
Plaque (most common)
Guttate
Palmoplantar
Inverse
Erythrodermic pustular
Clinical features of plaque psoriasis?
Plaques: well-circumscribed, erythematous, silver scaling
Seen on extensor surfaces, scalp
Itching
Clinical features of guttate psoriasis?
Raindrop-like red lesions
Many of them, scaly
Seen on trunk
Follows a strep. infection by about 2 weeks
What is palmoplantar psoriasis?
Thickening of palms and soles
Hyperproliferation of keratin layer
Clinical features of Inverse psoriasis?
Erythematous, non-scaly plaques, more widespread rather than individual plaques
Seen in flexures: sub-mammary, axillary, anogenital
Clinical features of erythematous pustular psoriasis?
Systemic disease
- malaise
- pyrexia
- circulatory problems
Widespread intense inflammation of the skin
Can be fatal
How can erythematous pustular psoriasis become fatal?
Widespread inflammation of the skin means severe dehydration, loss of water through the skin (like in burns patients)
What is onycholysis?
When the nail is lifted off the nail bed due to hyperkeratinosis
Occurs in psoriasis
Diagnosis of psoriasis?
Clinical: look at rash, it is usually quite specific
Family history
What are some risk factors for getting psoriasis?
Family history: genetic involvement
Drugs UV light Alcohol Stress Strep. infections (guttate)
What is Koebner’s phenomenon?
When psoriasis develops at the site of an injury, a cut for example
Topical treatments of psoriasis?
Emollients
Vitamin D analogues:
- Calcipotriol
Coal tar
Dithranol
Corticosteroids
Retinoids
Salicylic acid: cocois
What are vitamin D analogues and how do they work?
They decrease cell proliferation
Calcipotriol
How does coal tar help psoriasis?
Inhibits DNA synthesis
Systemic treatments of psoriasis?
Immunosuppressants
- methotrexate
- ciclosporin
Oral retinoids
Phototherapy:
- UVB
- PUVA
Biologics:
- anti-TNF
What is PUVA?
Psoralen combined with UVA light therapy
