Inflammatory Skin Disease - Psoriasis and Eczema

Question 1

What is the pathophysiology of psoriasis?

Answer 1

• Hyperproliferative disorder where mitotic activity of basal cells and suprabasal cells is significantly increased, with cells migrating from the basal layer to the stratum corneum in just a few days
• Caused by T cell mediated autoimmune disease where there is an abnormal infiltration of T cells
• Leads to release of inflammatory cytokines (IFN, interleukins, TNG)
• Also leads to increased keratinocyte proliferatons

Question 2

What genetic factors are associated with psoriasis?

Answer 2

• PSORS genes (PSORS1 - chromosome 6)
• HLA-Cw0602

Question 3

What does plaque psoriasis look like?

Answer 3

• Thickened erythematous plaques with silver scales
• Extensor surfaces and scalp
• Well defined
• Raised >1cm
• Onycholysis and pits
• Most common form in adults

Question 4

What does guttate psoriasis look like?

Answer 4

• Second most common type
• Small raised papules across trunk and limbs
• Mildly erythematous
• Often triggered by streptococcal throat infection
• Comes in waves
• Tear drop shaped?

Question 5

What does erythrodermic psoriasis look like?

Answer 5

• Extensive erythematous inflamed areas covering most of the surface area of the skin
• Medical emergency

Question 6

What does pustular psoriasis look like?

Answer 6

• Yellow pustules present
• Not infectious
• Patients can be systemically unwell and so require admission to hospital

Question 7

How is psoriasis treated?

Answer 7

• Clinical diagnosis based on appearance
• Can use biopsy
• Topical creams and ointments (moisturisers, steroids, vitamin D analogues, coal tar, topical retinoids)
• Phototherapy light treatment (immunosuppressant)
• Acitretin
• Methotrexate (immunosuppressant)
• Cilosporin (immunosuppressant)
• Biologic therapies (infliximab, enteracept, adalumimab)

Question 8

What conditions are associated with psoriasis?

Answer 8

• Psoriatis arthritis
• Metabolic syndrome
• Liver disease/alcohol misuse
• Depression

Question 9

How does eczema (dermatitis) present in the skin?

Answer 9

• Inflammation primarily due to inherited abnormalities in skin ‘barrier defect’
• Causes increased permeability and reduces it’s antimicrobial function
• Inherited mutation in filaggrin expression (filament-associated proteins which bind kerratin fibres in epidermal cells - gene on chromosome 1)
• Dry, red, itchy and sore patches of skin over the flexor surfaces and on the face and neck

Question 10

What is atopic eczema?

Answer 10

• Itchy inflammatory skin condition where the skin has thickened and areas of ulceration are present
• Poorly defined, associated with asthma, allergic rhinitis, conjunctivitis and hayfever
• High IgE immunoglobulin antibody levels

Question 11

What is seborrhoeic eczema?

Answer 11

• Chronic, scaly inflammatory condition
• Face, scalp and eyebrows and occasionally upper chest
• Overgrowth of Pityrosporum Ovale yeast

Question 12

What is varicose eczema?

Answer 12

• Underlying venous disease and affects lower legs
• Incompetence of deep perforating veins and increased hydrostatic pressure

Question 13

What is contact (allergic) eczema?

Answer 13

• Precipitated by an exogenous substance (type IV hypersensitivity)
• Allergens include nickel, chromate, cobalt, colophony and fragrance

Question 14

How is eczema treated?

Answer 14

• Atopic (emollients, topical steroids, bandages, antihistamines, avoidance, antibiotics/antifungals)
• Seborrhoeic (anti yeast shampoo, antimicrobials, topical steroids)
• Varicose (emollients, topical steroids, compression bandages, surgery)
• Contact (avoidance)

Question 15

What are the key diffeneces between eczema and psoriasis?

Answer 15

Question 16

What histological features are seen in psoriasis?

Answer 16

• Intra-epidermal spongiform pustules and Munro neutrophilic microabscess within stratum corneum
• Focal parakeratosis
• Epidermal acanthosis with dilated capillaries with dermal papillae

Question 17

What are the triggers of psoriasis?

Answer 17

• Stress
• Injury to skin
• Medications (lithium, anti-malarials, BBs)
• Infection

Question 18

What are common triggers of eczema/atopic dermatitis?

Answer 18

• Allergens (dust mites, pollen, molds, animal dander)
• Harsh soaps/detergents
• Wearing wool
• Workplace irritants
• Weather changes (especially dry and cold)
• Stress
• Certain foods (eggs, peanuts, milk, soy, wheat)
• Excessive washing

Question 19

The steroid ladder

Answer 19

• Mild - hydrocortisone
• Moderate - eumovate
• Potent - Betnovate
• Very potent - dermovate

Question 20

Specific signs suggestive of psoriasis

Answer 20

• Auspitz sign (small points of bleeding when plaques scraped off)
• Koebner phenomenon (development of psoriatic lesions to skin affected by trauma)
• Residual pigmentation