Psoriasis
Title
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Psoriasis
Definition
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A chronic inflammatory skin
disease
Which has:
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A number of clinical
manifestations
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The most common being red
plaques with silvery scales
Pathogenesis
Triggering Factors
Infections
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Streptococcal pharyngitis:
Characteristically provokes guttate psoriasis
Trauma
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Generates new lesions:
Koebner’s phenomenon
Drugs
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Lithium salts
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Antimalarials
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Rapid withdrawal of systemic
steroids
Toxins
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Alcohol
E&M
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Hypocalcaemia
Physical Agents
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Ultraviolet light
HLA Associations
Close association with:
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HLA-CW6
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HLA-DR7
Psoriasis with ankylosing spondylitis type of
arthritis
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HLA-B27
Pathological Process
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T cell activation
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Release of cytokines
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Acanthosis
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Parakeratosis:
Abnormal retention of nuclei in stratum corneum
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Neutrophil abscesses in upper
dermis
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Epidermal rete ridges elongated
and clubbed
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Capillary dilatation in dermis
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Perivascular infiltrate with
neutrophils, lymphocytes, histiocytes
Clinical Features
History
Age
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Any age
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Most common at puberty and
menopause
IS
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Pruritus:
Not inevitable
Examination
IS
Skin
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Discoid psoriasis (chronic
plaque psoriasis):
Well-defined red plaques with silvery scales
May be found at any site
Common sites are knees, elbows, extensor
surfaces of limbs, lower back
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Flexural psoriasis:
Psoriasis of axillae, groins, beneath the breasts
Plaques are smooth, more sharply defined than
eczema, symmetrical
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Scalp psoriasis:
Thick scaling
Face spared
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Palms and Soles:
Hyperkeratotic
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Guttate psoriasis:
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Numerous scaly papules and plaques:
Like raindrops
Occurs mainly in the 7-14 age group
Following streptococcal infections
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Erythrodermic psoriasis:
Total involvement of the skin
May result in hypothermia and hypoproteinaemia
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Pustular psoriasis:
This may be localised to the palms and soles
or generalised
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In the generalised type the
patient is ill with fever and leucocytosis:
Zumbush disease
Nails
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Pitting
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Onycholysis
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Subungual keratosis
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Thickening and distortion of
nails
LMS
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Distal arthropathy:
Affects terminal interphalangeal joints
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Rheumatoid like arthropathy:
But more asymmetrical
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Sacroiliitis and ankylosing
spondylitis
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Arthritis mutilans
Management
Control
Drugs
Topical therapy
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Tar
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Dithranol
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Steroids:
Limited role
Withdrawal causes a rebound flare
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Calcipotriol
Photochemotherapy
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Psoralens and ultraviolet light
Systemic Therapy
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Methotrexate
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Ciclosporin
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Retinoids
Biological Agents
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TNF alpha blockers:
Infliximab, adalimumab, etanercept
Prognosis
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Chronic plaque psoriasis:
Lifelong with remission at times, varying
severity
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Guttate psoriasis:
Resolves spontaneously after a few months, some
recur, some do not recur
