Psoriasis

Question 1

Definition

Answer 1

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

Question 2

Aetiology

Answer 2

· UNKNOWN

· Genetic, environmental factors and drugs are implicated

Question 3

Risk factors

Answer 3

o Guttate psoriasis - streptococcal sore throat

o Palmoplantar psoriasis - smoking, middle-aged women, autoimmune thyroid disease

o Generalised pustular psoriasis - hypoparathyroidism

Question 4

Epidemiology

Answer 4

· Affects 1-2% of population

· Peak age of onset: 20 yrs

Question 5

Presenting symptoms

Answer 5

· Itching and occasionally tender skin

· Pinpoint bleeding with removing scales (Auspitz phenomenon)

· Skin lesions may develop at sites of trauma/scars (Koebner phenomenon)

Question 6

Signs on physical examination (types)

Answer 6

· 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

Question 7

Signs on physical examination (nail signs)

Answer 7

o Pitting
o Onycholysis
o Subungual hyperkeratosis

Question 8

Signs on physical examination (joint signs)

Answer 8

· Joint Signs - FIVE presentations of psoriatic arthritis

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

Question 9

Investigations

Answer 9

· 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