Psoriasis

Learning objectives

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)

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

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

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)

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