Psoriasis Flashcards
What are the 2 key abnormalities in a psoriatic plaque?
Keratinocyte hyperproloferation
Inflammatory Cell Infiltrate (neutrophils. TNF, T cells)
What causes proliferation of endothelial cells in the superficial dermis?
Vascular endothelial growth factor
What are precipitating factors for psoriasis?
- Trauma (Kobner phenomenon)
- Infection
- Hormonal (improves in pregnancy, worse post partum)
- Drugs (antimalarials, B-blockers, IFN-a, lithium)
- Smoking and alcohol
- Emotion
What are the 5 main histological features?
- Parakeratosis
- Irregular thickening of epidermis over rete ridges, but thinning over dermal papillae
- Epidermal polumorphonuclear leucocyte infiltrates and microabscesses
- Dilated and torturous capillary loops in the dermal papillae
- T-cell infiltrate in upper dermis
What is Auspitz sign?
plaques bleed when scratched off
What is the typical distribution of plaque psoriasis?
Symmetrical sites on elbows, knees, lower back and scalp
Describe the typical presentation of guttate psoriasis
seen in children/teenagers post streptococci tonsillitis
numerous small, round, red macules suddenly appear on trunk- become scaly after short period of time
Often clears in a few months, may develop plaque psoriasis later on.
What are some signs of psoriasis on the nails?
thimble pitting
onycholysis
How does flexural psoriasis present?
women/elderly/HIV-affected
sites= submammary, axillary, anogenital folds
glistening, sharply demarcated, red plaques (+/- fissuring in depth of the fold)
what proportion of patients go on to develop psoriatic arthritis?
5-10%
what are the presentationsof psoriatic arthritis?
- Distal: DIP joints of fingers and toes (seen with marked fingernail changes)
- Single large joint
3 RA mimic - Sacro-Iliac Joints and spine
What tests would be carried out to diagnose psoriatic arthritis?
Rheumatoid factor (negative) HLA-B27 in patients with sacroiliitis
