Psoriasis Flashcards
Define Psoriasis
Psoriasis is a chronic autoimmune skin disease that speeds up the growth cycle of skin cells.
lesions of psoriasis?
sharply demarcated, erythematous, scaly plaques
on the extensor surfaces of the knees and elbows but can also affect the scalp and back.
What is the underlying mechanism of psoriasis?
An increase in the turnover rate and proliferative time of the dermal cells
-> from normal 26-28 days life to 3-5 days
Psoriasis -causes?
multifactorial;
- genetic factor -> important for treatment
- immune factors ->release of cytokines by activated t-cells-> inflammation -> higher skin proliferation
Psoriasis- usual onset
two “peaks”
- 30-39 yrs
- 50-69 yrs
genetic prevalence
every 1/3 has a affected relative
both parents are affected -> 50% chance of disease for child
Psoriasis - risk factors
- family history
- smoking
- alcohol
- obesity
- medication (beta-blockers, lithium, chloroquine)
- infections (post-strep, HIV)
Most common type of psoriasis
Plaque psoriasis
Plaque psoriasis - skin features
- symmetrical distribution
- scalp, knees, extensor surfaces of elbows, gluteal cleft
- worse in winter (dry air, lack of sunlight)
- Auspitz sign = minor bleeding beneath lesions/scale
definition of Auspitz sign
appearance of small bleeding points after successive layers of scale have been removed from the surface of psoriatic papules or plaques.
Guttate psoriasis
“drop-like psoriasis”
- acute eruptions (small plaques, <1cm) preceded by strep infection
- trunk, proximal extremities
Psoriasis - primary defect?
1) Genetic keratinocyte hyperproliferation ! reduces skin barrier, antigens can
penetrate and cause immune response
2) Genetic tendency for wrong healing response after different traumas
3) Increase in keratinocyte proliferation due to inflammatory cell mediators or signalling -> immune reaction
Pustular psoriasis - features
possibly live threatening
- sudden onset
- leukocytosis, malaise, fever, hypocalcemia
- Triggers: pregnancy, withdrawal of oral glucocorticoids
skin lesions: excessive pustules all over the body
Erythrodermic psoriasis
=head-to-toe generalized erythema
>90% body surface affected -> low barrier protection
- issues with sepsis, fluid loss
- higher risk of infection (bc of dry skin)
Inverse psoriasis
in skin folds
-no visible scaling
