Psoriasis

Psoriasis 

Updated: 02/10/2021

© Jun Wang, MD, PhD

General features
  • Chronic, multifactorial inflammation
  • Common; affects 1-2% of population, all ages, slightly more common in women
  • May be associated with arthritis, myopathy, enteropathy, and AIDS 
  • Symptoms tend to wax and wane, associated with systemic and environmental factors
  • Triggering factors
Cold
Trauma
Infections
Alcohol
Drugs
Stress
  • Beneficial factors
Hot weather
Sun light
Pregnancy status
  • Possibly life threatening if with fever, leukocytosis, diffuse infections, and electrolyte disturbances
  • Usually clinical diagnosis
Pathogenesis
  • Unclear, likely immune-mediated
  • Increase in the epidermal cell turnover rate with accompanied activated T cell infiltration
  • Elevated levels of cytokines, such as tumor necrosis factor-a, interferon-g, interleukin-12, interleukin-17
  • Certain genetic factors: deletion of late cornified envelop genes, HLA-Cw6, obesity
Clinical features
  • Either localized (hands/feet) or generalized 
  • Five major types
    • Plaque
    • Inverse: flexural surfaces and skin folds, DDx dermatophytosis
    • Guttate
    • Erythrodermic: Widespread red skin with diffuse fine peeling scale
    • Pustular
  • Worsening or sudden onset
  • Scaly area redness
  • Pain (especially in erythrodermic psoriasis and psoriatic arthritis)
  • Pruritus (especially in eruptive, guttate psoriasis)
  • Dystrophic nails: pits on nails, thickening, yellowish discoloration
  • Joint manifestation: Psoriatic arthritis, etc
  • Ocular involvement: Conjunctivitis or blepharitis
  • Auspitz sign: punctate bleeding spots when psoriasis scales are scraped off, non-specific
Plaque psoriasis
  • Most common
  • Rarely life threatening
  • Commonly on extensor surfaces
  • Raised well demarcated erythematous papules or plaques
  • Dry, thin, silver to white scales
Guttate psoriasis
Pustular psoriasis
  • Widespread pustules on erythematous background
  • Acute, subacute and chronic
  • Acute generalized type usually accompanied by fever, may be life threatening if not managed properly
Psoriatic arthritis
  • Common in patients with psoriasis 
  • May occur before the onset of psoriasis
  • Seronegative oligoarthritis
  • Onset or exacerbation may be associated with trauma
  • May start with stiffness and pain
  • First affects DIP of hands and feet; similar to rheumatoid arthritis but milder
  • Inflammation of digital tendon sheaths causes sausage fingers
  • May develop erosive and deforming arthritis
Pathological features
Management
  • Immunosuppressant: methotrexate, cyclosporine, etc


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