Psoriasis Flashcards
How does psoriasis arise?
Genetic susceptibility - PSOR1 on chromosome 9 (and other genes controlling inflammatory mediators)
Once the condition begins what immune response commences?
T cells move out of the blood vessels to the dermis causing a release of cytokines which in turn cause the skin to become inflamed and thickened. More keratinocytes are produced.
Describe the histology of psoriasis
Thickening of stratum corneum, parakeratosis and white blood cells in the epidermis forming abscesses. Spongiosis & oedema in dermal papillae
What is the name given to the abscess that form due to the WBC in the dermis?
Munro micro-abscesses
Name the common sites of psoriasis
- extensors
- scalp
- sacrum
- palms and soles
- nails
What is the key clinical feature for a psoriasis diagnosis?
Sharply demarcated scaly erythematous plaques
State two special signs that feature in psoriasis
Koebner phenomenon
Auspitz Sign
What is Koebner phenomenon?
After trauma psoriasis occurs in a previously unaffected area
What is Auspitz sign?
Removal of scale reveals tiny leading points due to dilated capillaries
Name five types of psoriasis
Vulgaris Guttate Palmoplantar Pustular Erythrodermic
Describe psoriasis vulgaris
Multiple areas of red, raised, scaly plaques
Describe guttate psoriasis
Often presents in children, multiple small red scaly lesions scattered over trunk and limbs found a few days after a strep throat infection
Describe palmoplantar psoriasis
Psoriasis of the palms and soles but can be found on other areas, often with pustular involvement
Describe pustular psoriasis
Rare type where the plaques have pus filled spots (found in the palms of smokers). Acute is a medical emergency but chronic in smokers is not.
Describe erythrodermic psoriasis
Aggressive form that often affects the whole body causing the skin to become very red and scaly this can lead to increased fluid and protein loss, mild heart failure, hypothermia
