Psoriasis

Question 1

Define

Answer 1

A chronic inflammatory skin disease, which has characteristic lesions and may be complicated by arthritis

•Long lasting autoimmune disease

Question 2

Causes

Answer 2

aetiology unknown
Genetic environmental factors and drugs (e.g. may be triggered by streptococcal infections, antimalarial agents, β-blockers, lithium)

5 main types

1. Plaque (90%) - red patches, scales on top
2. Guttate - drop-shaped lesions
3. Inverse - red patches in skin folds
4. Pustular - small non-infectious pus filled blisters
5. Erythrodermic - very widespread rash, develops form other types

Question 3

Epidemiology

Answer 3

1-2% of population Peak onset age 20 years

Question 4

Symptoms

Answer 4

• Itching, occasionally tender skin
• Pinpoint bleeding with removing scales (Auspitz phenomenon)
• ±Skin lesions may develop at site of trauma/scars (Koebner phenomenon)

Question 5

Signs

Answer 5

Discoid/Nummular psoriasis - symmetrical, well-demarcated erythematous plaques with silvery scales over extensor surfaces (knee, elbows, scalp, sacrum)

Flexural psoriasis - less scaly plaques in axilla, groins, perianal and genital skin

Guttate psoriasis - small drop-like lesions over trunk and limbs

Palmoplantar psoriasis - erythematous plaques with pustules on palms and soles

Generalised pustular psoriasis - pustules distributed over limbs and torso

Nail Signs

• Pitting
• Onycholysis
• Subungual hyperkeratosis

Joint Signs - FIVE presentations of psoriatic arthritis

• Asymmetrical oligoarthritis
• Symmetrical polyarthritis
• Distal interphalangeal joint predominance
• Arthritis mutilans
• Psoriatic spondylitis

Question 6

Investigations

Answer 6

• Most patients DO NOT need investigations
• Guttate psoriasis -anti-streptolysin-O titre, throat swab
• Flexural psoriasis - skin swabs to exclude candidiasis
• Nail clipping analysis for onychomycosis (fungal infection)
• Joint involvement analysed by checking for rheumatoid factor and radiographs