Learning objectives

• Define and classify the different types of psoriasis
• Describe psoriasis triggers
• Anesthetic management of a patient with psoriasis

Definition and mechanisms

• Psoriasis is a chronic skin disorder characterized by an accelerated epidermal turnover and epidermal hyperplasia
• Autoimmune disease resulting from an increased rate of epidermal protein synthesis, rapid epidermal cell growth, shortened epidermal cell cycle, and increase in the proliferative cell population
• Lesions consist of sharply demarcated, loosely adherent, thickened, noncoherent, silver skin scales with increased vascularity → they most commonly appear on the extensor surfaces (i.e., elbows and knees), lumbar-sacral area, and scalp 
• Injury to the skin can trigger psoriatic skin changes at that spot (Koebner’s phenomenon) 

Classification

• Plaque psoriasis or psoriasis vulgaris
  • Most common type (85-90%)
  • Causes dry, itchy, raised skin patches (plaques) covered with scales
  • Most commonly found on the elbows, knees, scalp, and back
• Nail psoriasis
  • Affecting fingernails and toenails
  • Causes pitting, abnormal nail growth, and discoloration
  • Nails might loosen and separate from the nail bed (onycholysis)
• Guttate psoriasis
  • Primarily affects young adults and children
  • Triggered by a bacterial infection (e.g., strep throat)
  • Marked by small, drop-shaped, scaling spots on the trunk, arms, or legs
• Inverse psoriasis
  • Mainly affects the skin folds of the armpits, groin, buttocks, and breasts
  • Causes smooth patches of inflamed skin that worsen with friction and sweating
  • Fungal infections may trigger this type of psoriasis
• Pustular psoriasis
  • Causes clearly defined pus-filled blisters
  • Occur in widespread patches or on small areas of the palms or soles
• Erythrodermic psoriasis (erythroderma)
  • Least common type
  • Widespread inflammation and exfoliation of the skin over most of the body surface (>90% of the body surface area)
  • Accompanied by severe dryness, itching, swelling, and pain
  • Can develop from any type of psoriasis

Signs and symptoms

• Patchy rash ranging from spots of dandruff-like scaling to major eruptions across the entire body
• Rashes that vary in color (purple with gray scale to pink-red with silver scale)
• Small scaling spots
• Dry, cracked skin that may bleed
• Itching, burning, or soreness
• Cyclic rashes that flare for a few weeks or months and then subside
• Psoriatic lesions become colonized by bacteria (especially Staphylococcus aureus) 
• Severe psoriasis may be associated with hyperuricemia, anemia, negative nitrogen balance, iron loss, and hypoalbuminemia

Complications

• Psoriatic arthritis, which resembles seronegative rheumatoid arthritis
• Temporary skin color changes (postinflammatory hypo- or hyperpigmentation) where plaques have healed
• Eye conditions (e.g., conjunctivitis, blepharitis, and uveitis)
• Obesity
• Diabetes type 2
• Hypertension
• Cardiovascular disease
• Other autoimmune diseases (e.g., ulcerative colitis, Crohn’s disease, celiac disease, or multiple sclerosis)
• Increased risk of developing non-melanoma skin cancer
• Mental health conditions (e.g., low self-esteem and depression)

Risk factors

• Genetic (HLA-Cw6)
• Family history
• Smoking

Psoriasis triggers

• Infections (e.g., strep throat or skin infections)
• Weather (cold and dry)
• Injury to the skin (e.g., cut or scrape, bug bite, or severe sunburn)
• Stress
• Smoking and exposure to secondhand smoke
• Obesity
• Heavy alcohol consumption
• Certain medications (e.g., lithium, beta-blockers, calcium channel blockers, antimalarial drugs, NSAIDs)
• Rapid withdrawal of oral or injected corticosteroids

Treatment

• Topical therapy
  • Corticosteroids (i.e., hydrocortisone)
  • Vitamin D3 analogs (i.e., calcipotriene and calcitriol) to slow skin cell growth
  • Retinoids/vitamin A derivatives (i.e., tazarotene)
  • Calcineurin inhibitors (i.e., tacrolimus and pimecrolimus) to calm the rash and reduce the scaly buildup
  • Salicylic acid to reduce the scaling of scalp psoriasis
  • Coal tar to reduce scaling, itching, and inflammation
  • Anthralin to slow skin cell growth
• Phototherapy
  • Sunlight
  • UVB broadband and narrowband
  • UVB
  • PUVA
• Oral or injected (systemic) medications
  • Corticosteroids 
  • Retinoids/vitamin A derivatives
  • Biologics (i.e., apremilast, etanercept, infliximab, adalimumab, etc.) to suppress the immune system
  • Methotrexate to decrease the production of skin cells and suppress inflammation
  • Cyclosporine to suppress the immune system

Management

Suggested reading

• Pollard BJ, Kitchen G. Handbook of Clinical Anaesthesia. 4th ed. Taylor & Francis group; 2018. Chapter 9 Connective tissue, Lomas JP.