Psoriasis

Snapshot

A 42-year-old man presents to his dermatologist for management of his psoriasis. He reports an itchy and rough rash along his elbows, knees, and scalp. While he was previously treated for this disease in childhood, he has been off treatment for years. Physical exam reveals 2-7 cm pink plaques with overlying silvery scales. When the scale is scratched off, there is pinpoint bleeding. He is started on an intensive topical therapy regimen with corticosteroids and vitamin D analog.

Introduction

Clinical definition
- idiopathic and chronic inflammatory disease characterized by silver scales and thickened skin
  - most common subtype is plaque psoriasis
Epidemiology
- incidence
  - US incidence
    - 2% of population
- demographics
  - normallly, > 40 years of age but can affect people of all ages
- risk factors
  - smoking
  - skin trauma
  - alcohol abuse
  - stress
  - cold weather
Etiology
- idiopathic
- drugs
Pathogenesis
- hyperproliferation of basal stem keratinocytes
- ↑ inflammation, especially inflammatory markers IL-6, C-reactive protein, TNF-α, E-selectin, ICAM-1
Associated conditions
psoriatic arthritis

Presentation

Symptoms
- painful or pruritic skin lesions
- joints may be painful or stiffens
  - especially in feet and hands
Physical exam
- well-circumscribed, pink papules and flat-topped plaques with silvery scales
- common locations
  - scalp
  - trunk
  - buttocks
  - extensor surface of limbs
- positive Auspitz sign
  - when scales are scraped off, there is pinpoint bleeding
    - results from exposure of dermal papillae
nail pitting

Studies

Labs
- electrolytes
  - there may be electrolyte imbalances if psoriasis is extensive
Histology
- acanthosis with parakeratosis (thickened stratum corneum with retained nuclei)
- Munro microabscesses
- ↑ stratum spinosum
↓ stratum granulosum

Differential

Treatment

Complications