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Psoriasis

Diagnosis & Management

Dr Rowan Brown

February 2009

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Pathogenesis

Hyperproliferation of keratinoctyes secondary to cytokine stimulus

Epidermal thickening (acanthosis)

Neutrophil/Lymphocyte infiltration

Development of micro-abscesses in the corneum stratum

Development of dilated capillaries in the dermis (resulting in bleeding points)

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Histology

hyperkeratosis

microabscess

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Aetiology

Immune mediated: antigen exposed within the corneum stratum

associated features

HLA CL6 (genetic)

Infection: Streptococcus → guttate psoriasis

Stress → exacerbations

Drugs → Alcohol, β-blockers +nsaids

Koebner Phenomenon (occurring in scar tissue)

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Clinical Features8 clinical subtypes

psoriasis vulgaris (most common)

guttate psoriasis (post infective)

flexoral psoriasis

erythrodermic psoriasis

palmoplantar psoriasis

psoriatic arthritis

nail psoriasis

acute pustular psoriasis

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Acute Pustular Psoriasis

Widespread sterile pustules

These coalesce to form “lakes of pus”

Caused by withdrawl of steroids drugs, pregnancy

Septicaemia

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Psoriasis Vulgaris (Plaque)

Common 0.5-3% of population

Single or multiple plaques

Age 15-40 (mean age 28yrs)

Extensor surfaces, back, sacrum,

hairline, knees, elbows

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Guttate Psoriasis

Multiple small lesions post infection

Often spontaneously resolve in 2-3/12

Respond poorly to topical agents

Differential with pityriasis

(scale confined to edge of lesions)

pityriasis rosacea - scale confined to

edge

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Flexural PsoriasisTypical eczema distribution

Often associated with psoriasis in the hair.

Differential with intertrigo

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Erythrodermic Psoriasis

Results when 90% of body affected

Precipitated by withdrawl of steroids

Consequences:

infection

dehydration

high out-put cardiac failure

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Palmoplantar Psoriasis

Vesicles on soles of hands & feet

Painful rather than itchy

Chronic condition

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Psoriatic Arthritis

5 main clinical subtypes:

symmetrical polyarthritis

asymmetrical oligoarthritis (large joint)

spondylitic (sero-negative)

distal-interphalangeal (nail)

severe mutilans

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Nail Psoriasis

50% of patients with skin involvement

90% of psoriatic arthritis

pitting

onycholysis of distal nail bed

subungal hyperkeratosis

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Treatment

Predominately benign + chronic condition

Topical/Systemic Treatments

Topical: - good for single isolated lesions

Tar - based preparations

Vitamin D-analogues

Steroids (rebound)

Dithranol (inhibits mitochondrial DNA)

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Treatment

Systemic

UVB (nUVB = 311nm wavelength, is more effective)

PUVA = Psoralen + UV light

Useful for multiple lesions, erythrodermic psoriasis, pustular psoriasis

methotrexate (hepatic fibrosis + myelosuppression)

cyclosporin (hypertension, hypertrichosis, skin malignancy +lymphoma)

retinoids (good for pustular psoriasis)