Psoriasis

Question 1

Define psoriasis

Answer 1

Chronic inflammatory skin disease characterised by erythematous, circumscribed scaly papules, and plaques due to hyperproliferation of keratinocytes

Question 2

Aetiology of psoriasis

Answer 2

epidermal hyperproliferation + abnormal keratinocyte differentiation + lymphocyte inflammatory infiltrate

Triggers:
Stress
Smoking
Alcohol
Drugs (antimarial, beta-blockers, ACEi, terfenadine, penicillin, tetracycline, lithium)
Infection: streptococcal (guttate)
Trauma: scratching, piercing, tattoos, burns, surgery
Hormonal changes: puberty, post-partum, menopause
HIV and AIDs

Question 3

Types of psoriasis

Answer 3

Chronic plaque (psoriasis vulgaris): most common (80-90%)
Localised pustular
Flexural
Guttate
Erythrodermic
Generalised pustular
Nail

Question 4

What is psoriasis associated with

Answer 4

Psoriatic arthritis
Metabolic syndrome: obesity, hyperlipidaemia, HTN, T2DM, NAFLD
IHD
IBD
Anxiety and depression
VTE
Non-melanoma skin cancer
Lymphoma

Question 5

What are the features of psoriatic arthritis

Answer 5

Seronegative inflammatory arthritis
Skin psoriasis often develops before joint involvement (typical lag time of 5-10 years)
Inflammatory pain or peripheral joint swelling especially affecting the knees, ankles, hands, and feet; or dactylitis (swelling and tenderness of an entire digit)
Inflammatory or night-time pain in the axial skeleton and at tendon insertions (enthesitis), especially affecting the Achilles tendon and/or plantar fascia.
Nail changes

1. Monoarthritis
2. Distal asymmetrical oligoarthritis (interphalyngeal joints)
3. Dactylitis 
4. Rheumatoid arthritis-like (symmetrical polyarthritis)
5. Arthritis mutilans (telescoping)
6. Ankylosing spondylitis

Question 6

Features of plaque psoriasis

Answer 6

Most common
Symmetrical well-demarcated erythematous plaques
Purple, silvery plaques
Dry, flaky skin
Itchy/painful
Distributed on extensors/scalp

Question 7

Features of pustular psoriasis

Answer 7

Plaques/pustules on palms + plantars
Limbs + torso
Medical emergency if generalised

Question 8

Features of guttate psoriasis

Answer 8

Raindrop plaques, small ~1cm
2-weeks post-strep

Question 9

Features of flexural psoriasis

Answer 9

Found on the body folds e.g. axilla, groin, peri-anal area

Question 10

Features of erythrodermic psoriasis

Answer 10

Systemic body redness and inflammation
Often temp. dysregulation, electrolyte imbalance
Requires hospitalisation

Question 11

General signs of psoriasis on examination

Answer 11

Nail signs: onycholysis, pitting, subungal hyperkeratosis, “salmon patch”

Pinpoint bleeding with removing scales (Auspitz phenomenon)
Skin lesions occurring at the site of trauma/scars (Koebner phenomenon)
Often worse in the Winter months (responds well to Sun)

Question 12

Management for psoriasis

Answer 12

Conservative:
Smoking cessation
Limit alcohol intake
Weight loss
Support life factors e.g. stress

Medical:
1st line (4w trial): OM corticosteroid (potent) and ON vitamin D analogue (alternate OM, ON)
- Start with potent steroids
- 4w break between steroids

2nd line (after 8w; n.b. 4w gap): OM corticosteroid (potent) and BD vitamin D analogue

3rd line: BD corticosteroid (4 weeks; potent) or coal tar (OD or BD)

Adjunct: Emollients (reduce scale loss, reduce pruritus)
Alternative: short-acting dithranol (wash off after 30m)

Question 13

Management of psoriasis in secondary care

Answer 13

Phototherapy (P-UVB, 3x/week) or photochemotherapy (P-UVA + psoralen)
Systemic medications (1st: methotrexate; other: ciclosporin, retinoids, biologicals…)
- Infliximab
- Etanercept
- Adalimumab
- Ustekinumab

Question 14

Describe the use of topical steroids in psoriasis

Answer 14

Maximum use:
- Potent → use for a maximum of 8 weeks at a time
- Very potent → use for a maximum of 4 weeks at a time
- 4 week breaks between courses of topical corticosteroids
SE: skin atrophy, striae, rebound symptoms

Question 15

Describe the use of vitamin D analogues in psoriasis

Answer 15

Calcipotriol, calcitriol, tacalcitol
MoA = reduces cell division + differentiation  reduced scaling/thickness but NO effect on erythema
Can be used long-term (adverse effects are uncommon, do not smell or stain)
Avoid in pregnancy

Question 16

Complications of psoriasis

Answer 16

Psychosocial: anxiety and depression | low self-esteem | relationship difficulties | limitation of activities requiring skin exposure
Physical:
Erythrodermic psoriasis
- Heart failure — due to increased skin blood flow, blood volume, and cardiac output.
- Malabsorption — enteropathy causes changes in intestinal absorption.
- Hypothermia — due to increased heat loss from the body surface.
- Dehydration — from increased transepidermal water loss due to the reduction in the barrier function of the skin.
- Mild anaemia — iron deficiency due to skin losses from excess scaling and impaired absorption and utilization of iron. Vitamin B12 and folate levels may also be low.
Generalised pustular: may be life-threatening and can cause fever, malaise, tachycardia, weight loss, and hypothermia
Pregnancy complications:
Risk of miscarriage, preterm delivery, low birthweight infants

Question 17

Prognosis for psoriasis

Answer 17

Plaque psoriasis is usually a chronic condition, but spontaneous remission may occur in up to 25% of people with psoriasis, and this may last for months
Guttate psoriasis is usually self-limiting and typically resolves within 3–4 months of onset. About a third of people with guttate psoriasis develop classic plaque disease
Early onset of disease is associated with being female and having an affected first-degree relative
Disease onset at an earlier age may predict more extensive, severe, and unstable disease.