Psoriasis Flashcards
define parakeratosis
inc in number of nuclei in keratin layer of epidermis (stratum corneum)
define papillomatosis
irregular epithelial thickening
what is the most common form of psoriasis
psoriasis vulgaris (chronic plaque psoriasis)
define psoriasis
chronic inflammatory dermatosis thought to be autoimmune mediated
characterised by well demarcated red, scaly plaques. The skin becomes inflamed and hyperproliferates at about ten times the normal rate
age of onset
two peaks
- younger is more common, and is usually associated with a psoriatic family history
- older peaks at around around 55-60
aetiology
regulation of epidermal turnover lost - hyperplasia . T cell driven inflammatory infiltration of dermis and epidermis
there is a genetic predisposition but it is also dependent on environmental factors
which T cells is psoriasis associated with
Th1 and Th17
is there epidermal or dermal involvement?
T lymphocyte driven inflammatory infiltration of dermis and epidermis
pathophysiology
polymorphs attracted to stratum corneum creating munro micro abscesses.
parakeratosis, acanthosis and thick keratin scale
epidermal rete ridges are elongated and clubbed
where are munro micro abscesses found
in the epidermis
what happens to the dermis
there is oedema and inflammation
what does the thick keratin scale indicate
epidermal involvement
what happens to the keratinocyte turnover time
normally 28 days, reduced to 7 days
what are munro micro abscesses
collection of neutrophils in the stratum corneum
what happens to the blood vessels
thick and tortuous
describe the plaques
thick, scaly, sharply demarcated erythematous plaques
symmetrical?
yes
what is the koebner phenomenon
- what diseases is it also seen in
new lesions at site of trauma
- lichen planus and vitiligo
what is Auspitz sign
removal of surface scale reveals tiny bleeding point due to dilated capillaries in elongated dermal papillae
what does sun do to lesions
improve them
itchy?
mildy
guttate
widespread small plaques on trunk and limbs
what is guttate preceded by
sore throat with group B haemolytic streptococcus
time of onset of guttate psoriasis
- Rash comes on very quickly, use in a couple of days
what shape can the guttate plaques be described as
tear drop
palmoplantar pustular
chronic condition with multiple sterile pustules on the palms and soles of feet
what does palmoplantar pustular first appear as
monomorphic yellow lesions
what is a serious life threatening form
erythrodermic or widespread pustular - RARE
features of erythrodermic
- Features are those of any form of erythroderma (red dry skin all over the body)
aetiology of erythrodermic
- Usually occurs in the setting of known worsening or unstable psoriasis, uncommonly is the first presentation of psoriasis
- May be precipitated by e.g. infection, withdrawal of steroids
psoriatic nail disease CF
oncholysis, nail pitting, dystrophy, subungal hyperkeratosis
subungal hyperkeratosis
excessive reproduction of skin cells that accumulate between the nail and the nail bed
oncholysis
pulling away of nail from bed due to abnormal cell adhesion
what is nail pitting due to
parakeratotic cells being los from surface
what are the treatment choices
vitamin D analogues
tar
dithranol
steroid ointments
emollients
phototherapy
IS
immune modulation
IS drug
methrotrexate
vitaminD analogues
calcipotriol (Dovonex) and calcitriol (silkis) ointment
what effect can emollients have if used regularly
anti inflammatory
what is this histological feature
spongiosis - oedema between keratoinocytes
what is this histological feature
papillomatosis - irregual epithelial thickening
name 3 drugs which aggravate psoriasis
- Beta blockers
- anti-malarials (hydroxychloroquine)
- lithium
- interferons
what adverse effect on the skin can steroids cause
skin atrophy
what adverse effect can dithranol cause
skin irritation, particularly of genitalia and eyes
which treatment is preferred by patients as it is the cleanest
vitamin D analogues
