2. Objectives
To understand the basic pathology of
psoriasis
To appreciate its different modes of
presentation
To be able to list the treatment options
To understand that psoriasis has a
significant burden on many people
3. Pathogenesis
Psoriasis is very common, affecting 1-2% of
most populations.
There is a strong genetic predisposition. It is
due to immune stimulation and increased
keratinocyte cell turnover.
The epidermis is hyperplastic (thickened)
and there is an infiltrate of neutrophils in
early lesions, followed by lymphocytes.
4. Chronic plaque psoriasis has been divided into two
groups base on age of onset and HLA
associations
Type 1 – presents in young adults. A family history
is common and 80% have HLA-Cw6. The
disease tends to be more severe.
Type 2 – peaks in incidence at 50 – 60 years of
age. Patients tend to have milder disease.
Psoriasis can present at any age, but 75% present
before the age of 40.
5. There is no single, exogenous cause but a
number of triggers for psoriasis
Infection - streptococcal, HIV
Skin trauma- koebnerisation
Drugs- lithium, NSAID’s, anti-malarials, β-
blockers, interferon, systemic steroid withdrawal
Stress- emotional or metabolic
6. Clinical features
The hallmark of psoriasis is a well defined scaly red plaque.
This may have a “salmon pink” hue. The scale can be
waxy or silvery.
Psoriasis is not characteristically itchy, but can be very
noticeable and greatly impair patients’ quality of life.
8. Categorization of psoriasis
Chronic plaque psoriasis – the most common form
that shows the most classic features
The nails and scalp are frequently involved
Flexural psoriasis – involving predominately the
groin and/or the axila
Pustular psoriasis – can be generalized or
localised
Palmoplantar psoriasis
Sebopsoriasis – overlapping features with
seborrheic dermatitis
Guttate psoriasis – many small, drop-like lesions
16. Natural History
The course of psoriasis is variable.
Generally it can be treated and sometimes
cleared. In some it may not recur for
several years and in others it may be very
severe and disabling.
Guttate psoriasis has a good prognosis.
Generalized pustular psoriasis is often very
difficult to treat
17. Management
There are four main categories
General measures
Topical treatment
Ultraviolet treatment
Systemic agents
18. General measures
It is very important for patients to look after their health
generally, both to help control the psoriasis and due to
its known co-morbiditities
Sympathetic explanation of the disease, it’s natural history
and treatment options is an essential part of
management
Avoidance of stress – sometimes a hospital admission can
provide a break from this
Treatment of blood pressure, cholesterol, any diabetes and
weight is also important and should be assisted by the
GP
Cessation of smoking
Generally, a balanced healthy diet and regular exercise are
important
20. Simple emollients (eg sorbolene) can help
with the scaling and dryness of psoriasis.
Keratolytics (eg salicylic acid) can be
added to these. Generally these are
tolerated well but only have a mild effect
on psoriasis.
21. Topical steroids are very helpful in
managing the inflammation of psoriasis.
They are especially useful in acute
inflamed plaques. Weak steroids are often
ineffective. However, strong steroids need
to be used for limited periods as psoriasis
tends to become more resistent to their
use (tachyphylaxis)
The strength is determined by the body site
and the severity. Typical examples are…
Mild flexural or facial involvement – Hydrocortisone 1% (eg sigmacort)
Mild to moderate body involvement – Methylprednisolone 0.1% (eg advantan) or mometasone (eg
elocon)
Severe, body involved or palms and soles - Betamethasone diproprionate 0.05% (eg diprosone)
22. Topical calcipotriol (daivonex) is a vitamin D analogue that
decreases the turnover of keratinocytes. It can be useful
in the long-term treatment of psoriasis. It has a very low
risk of tachyphylaxis or local side effects.
One product, daivobet, combines calcipotriol with
betamethasone diproprionate and is also effective for
flares of psoriasis.
23. Coal tar, pine tar and shale tar have all been used in
psoriasis
Coal tar is most frequently used now and is particularly
effective for chronic plaque psoriasis and scalp psoriasis.
Some patients do not like the associated “tarry” smell.
Occasionally they can irritate or aggravate psoriasis.
Tars are often used in combination with keraolytics
eg 6% LPC (liquor picis carbonis = crude coal tar) +4% salicylic acid in white soft paraffin.
24. Dithranol inhibits DNA synthesis and decreases the
epidermal hyperproliferation of psoriasis.
It produces redness and burning when applied to normal
skin and can cause brown staining of the skin and
clothing.
It is used in combination with ultraviolet therapy in Ingram’s
regime.
25. Ultraviolet therapy
Sunlight has long been known to have a benefit on
psoriasis.
A specific wavelength, 311nm, of UVB light has been
shown to have the best therapeutic effect on psoriasis
while minimizing side effects.
The dose is slowly titrated over 8-12 weeks until a good
response is achieved
Mild erythema is common, but more severe sunburn-like
reactions can occur. Over the long-term the skin will
become more tanned and naevi become darker. There is
an increased risk of skin cancer, but this is low.
27. Systemic treatments
These are only used in psoriasis failing to respond to
topical or ultraviolet treatment. Patients must be
monitorred closely for side effects.
Methotrexate and cyclosporin are essentially
immunosupressants that can be very effective but have
many possible short and long term side effects.
28. Acitretin normalizes epidermal keratinization. It is most
effective for psoriasis of the hands and feet and pustular
psoriasis such as this case.
29. There are now four “biologic” agents available to treat
psoriasis. These are injections that are approved in
patients with severe psoriasis who have failed the other
systemic treatments.
Infliximab, etanercept and adalimumab are tumour necrosis
factor alpha antagonists
Ustekinumab is a interleukin 12 and interleukin 23
monoclonal antibody.
These can be very effective but also have possible side
effects including the risk of unusual infections.
30. Conclusion
Psoriasis is very common.
Although it does not generally cause severe symtpoms, it
has a very significant psychosocial burden in many
patients.
Treatments are numerous and include topical treatments,
ultraviolet treatment and systemic treatment.
The condition is not curable but significant improvement
and often clearance can be achieved.
