Lecture 7: Psoriasis

Question 1

Describe the appearance of Psoriasis?

Answer 1

Numerous small sharply demarcated erythematous papules/plaques with a micaeceous scale

Question 2

Describe the appearance of Psoriasis in english?

Answer 2

Raised red clean-edged lesions with a sparkly scale.

Question 3

How does psoriasis affect the nails?

Answer 3

Psoriasis of the nails presents with:

• Onycholysis
• Pitting
• Oil spots

Question 4

What are koebner’s phenonmenon and Woronoff’s Ring?

Answer 4

Koebnor’s Phenomenon - Lesions appear directly at sites of injury on the skin

Woronoff’s Ring - A blanched halo around lesions following topical therapy

Question 5

Describe how Psoriasis biopsies appear histologically?

Answer 5

• Hyperkeratosis (Thickened stratum corneum)
• Munro’s Microabscesses (Neutrophils in S. Corneum)
• Psoriasiform Hyperplasia (Thick squamous cell layer, aka Acanthosis)
• Dilated dermal capillaries
• T cell infiltration

Question 6

Whats the DDX for Psoriasis?

Answer 6

Seborrhoeic Dermatitis
Lichen Planus
Mycosis Fungoides

Question 7

Describe the aetiology of Psoriasis?

Answer 7

A mixture of genetic susceptibility and an environmental trigger

Question 8

What genes determine Psoriasis susceptibility?

Answer 8

PSORS1-9 genes

Question 9

What are the main environmental triggers for Psoriasis?

Answer 9

Infection
Drugs
Trauma
Sunlight

Question 10

Age of onset is determined by a seperate gene?

Answer 10

HLA-Cw6

Question 11

When do most people develop Psoriasis?

Answer 11

Peaks at 20-30 and 50-60

But 75% occur before reaching 40

Question 12

What are the parts of Psoriasis’ pathogenesis?

Answer 12

Stressed Keratinocytes –> Th activation

Interleukins/TNF-alpha stimulate keratinocyte proliferation

Excess VEGF –> Angiogenesis

Neutrophils gather in acute disease causing pustules

Cell cycle is reduced from 28-5 days

Question 13

How do stressed keratinocytes leads to Th cell activation and what is the consequence?

Answer 13

Keratinocytes activate Dermal Dendritic Cells (dDC)
dDCs trigger lymph nodes to present uncertain antigen to naive T cells
T cells differentiate to Th1, 17 & 22

Th cells cause the plaque formation

Question 14

How is keratinocyte proliferation stimulated?

Answer 14

Interleukins and Anti-TNFalpha amplify the inflammatory cascade

Question 15

What are the risk factors for Psoriasis?

Answer 15

FH
Peak ages (20-30/50-60)
Smoking
Alcohol
CVD
Depression
Drug/Light therapies
Skin cancer
Metabolic syndrome

Question 16

What are the systemic signs of Psoriasis?

Answer 16

Psoriatic Arthritis
Psychosocial problems
Metabolic syndrome

Question 17

How is Psoriasis diagnosed?

Answer 17

CLinically

But if atypical take a biopsy and diagnose histologically

Question 18

How would you treat Psoriasis in the GP?

Answer 18

Soap Substitutes
Emollients
Coal Tar Creams

Vit D3 analogues
Topical Steroids (Genitals/flexures)
Salicylic acid (keratolytic)

Question 19

How do Vit D3 analogues help Psoriasis?

Answer 19

They inhibit epidermal proliferation

Question 20

How would a dermatologist treat Psoriasis?

Answer 20

Crude Coal Tar (Day or inpatient treatment)

Dithranol

UVB phototherapy (for Guttate)

Question 21

What are the systemic treatments for Psoriasis?

Answer 21

Retinoids

Immunosuppression

Biologics

Question 22

Describe retinoid use in Psoriasis?

Answer 22

E.g. Acitretin

You must monitor LFTs, lipids and educate that they’re teratogenic for up to 3 yrs post treatment

Question 23

Describe immunosuppresion use in Psoriasis?

Answer 23

Cyclosporin - Fast acting so good for initial treatment (risks renal damage)

Methotrexate - Good for Psoriatic Arthritis but risks marrow suppression and liver damage

Question 24

Describe biologic use in Psoriasis?

Answer 24

Anti-TNF e.g. Infliximab
ILK-12, 23 e.g. Ustekinumab

Patients can develop antibodies to these therapies

Question 25

How do we monitor patients with Psoriasis?

Answer 25

Psoriasis Area Severity Index (PASI)

Dermatology Life Quality Index (DLQI)

Question 26

List some variations of Psoriasis?

Answer 26

• Chronic plaque psoriasis
• Guttate Psoriasis
• Palmo-plantar Psoriasis
• Scalp Psoriasis
• Nail Psoriasis
• Flexure or Inverse Psoriasis
• Pustular Psoriasis
• Erythrodermic Psoriasis

Question 27

How does chronic plaque Psoriasis tend to present?

Answer 27

Large symmetrical plaques on the extensor surfaces

Particularly the backs of elbows/arms

Question 28

How does guttate Psoriasis occur/present?

Answer 28

In kids/adolescents following a viral/bacterial infection

It may develop into chronic plaque Psoriasis

Question 29

How do we investigate and treat Guttate Psoriasis?

Answer 29

ASO titre/History for recent infection

UVB phototherapy if it doenst resolve

Question 30

How does Palmo-plantar Psoriasis occur/present?

Answer 30

associated with smoking and sterile inflammatory bone lesions

Large plaques on the palms and soles

Question 31

Why is scalp Psoriasis important?

Answer 31

It can often be missed in examination

And it can lead to alopecia

Question 32

How is flexural or inverse Psoriasis different?

Answer 32

Often lacks a scale

Question 33

How does pustular Psoriasis occur/present?

Answer 33

Tiny sterile pustules in the plaques

IT occurs when:

• Pregant
• Hypocalcaemic
• Infected
• On rapid steroid withdrawel

Question 34

Whats particularly bad about Erythrodermic Psoriasis

Answer 34

Presents with fever

Rapid onset generalised erythema and lesions (>80% of body) +/- pustule clusters

Question 35

How do you manage Erythrodermic Psoriasis?

Answer 35

• Bloods (including excluding infection) [Elevated WCC]
• IV access
• Admit to hospital
• Thick/greasy emollient
• Fluid balance!!!
• Find the trigger
• Avoid steroids
• Systemic or Biologic therapy