Psoriasis

Question 1

What is psoriasis?

Answer 1

Chronic inflammatory skin disease with characteristic lesions and may be associated with arthritis.

Question 2

What is the aetiology of psoriasis? (x3)

Answer 2

• Unknown
• GENETIC
• INFECTION: certain types e.g., guttate associated with post-streptococcal URTI. Viral infection has also been linked to flares of psoriasis
• DRUGS: antimalarial agents, B-blockers and lithium

Question 3

What are the risk factors for psoriasis? (x5)

Answer 3

Smoking, autoimmune thyroid disease, obesity, beer, hypoparathyroidism.

Question 4

What is the pathophysiology of psoriasis?

Answer 4

Autoimmune hyperproliferation of keratinocytes in the epidermis AND upward migration of immature keratinocytes. Occurs due to inflammatory cascade in the dermis involving dendritic cells, macrophages and T cells. The silver scale associated with lesions is a layer of dead cells.

Question 5

What is the epidemiology of psoriasis: Age?

Answer 5

Peak age of onset is 28.

Question 6

GENERAL: What are the signs and symptoms of psoriasis?

Answer 6

Erythematous, circumscribed scaly papules and plaques which can be associated with pain and itching.

Question 7

What are the signs and symptoms of different types of psoriasis? (x4)

Answer 7

• PLAQUE: chronic, raised inflammatory plaques with superficial silver-white scale. Symmetrical spread and clear demarcation
• GUTTATE: widespread, erythematous, small, scattered, scaly papules on trunk, arms and legs
• PUSTULAR: acute, widespread erythema followed by eruption of white pustules which coalesce to form lakes of pus. Associated with fever and constitutional symptoms. Can also present in chronic forms: pustules on palms and soles.
• ERYTHRODERMIC: generalised erythema that affects more than 90% of skin with fine scaling associated with pain and irritation. May be associated with systemic illness

Question 8

What is psoriatic arthritis? Presentations? (x6)

Answer 8

In addition to skin lesions, there is joint involvement causing inflammation and deformity. There are 6 possible presentations: (1) monoarthritis, (2) distal asymmetrical oligoarthritis in DIP joints, (3) dactylitis, (4) rheumatoid arthritis-like symmetrical polyarthritis, (5) arthritis mutilans (shortening of digits – see photo), and (6) ankylosing spondylitis.

Question 9

What are the different types of psoriasis based on location? (x4)

Answer 9

• NAIL: nail pitting, discolouration (orange/yellow; known as oil drop or salmon spot), subungual hyperkeratosis, onycholysis (detachment) and nail dystrophy. Strong association with psoriatic arthritis
• FLEXURAL: affecting areas such as groin, axillae, abdominal folds, gluteal cleft
• SCALP: plaque psoriasis in scalp and may be associated with alopecia
• FACIAL: well-demarcated plaques on face

Question 10

What is Koebner phenomenon?

Answer 10

Skin lesions develop at site of trauma.

Question 11

What is Auspitz phemenon?

Answer 11

Pinpoint bleeding at area where scales have been removed.

Question 12

What are the investigations for psoriasis? (x4)

Answer 12

• Diagnosis mostly done through examination
• GUTTATE: throat swab and anti-streptolysin-O titre due to streptococcal aetiology
• FLEXURAL LESIONS: skin swabs to exclude candidiasis
• NAIL: analyse nail clipping to exclude fungal infection
• ARTHRITIS: rheumatoid factor negative