11/14/24, 10\:48 AM Psoriasis

Psoriasis

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Psoriasis\: chronic in
men and women, bimodal onset (15-25 and 50-60 years).
Aetiology\: autoimmune, T-cell mediated; genetic, immunological, and environmental factors; polygenic inheritance;
triggers include infections, hormonal changes, and medications.
Risk factors\: infections (streptococcal), hormonal changes, medications (lithium, chloroquine, steroids), trauma (Koebner
phenomenon), smoking, alcohol, stress; sunlight usually relieves symptoms.
Symptoms\: pruritic lesions, pain/burning sensation around lesions, joint pain/sti
often present.
Clinical features\: well-demarcated, erythematous plaques with overlying scale (except
distribution (scalp, elbows, knees); nail changes (pitting, onycholysis, yellowing, ridging).
Clinical presentations\: chronic plaque psoriasis (90% of cases), guttate psoriasis (small, scaly plaques post-infection),
erythrodermic psoriasis (severe, widespread in
Associated conditions\: psoriatic arthritis (10-30% of patients), in
metabolic syndrome (abdominal obesity, hypertension, dyslipidaemia, insulin resistance).
Di
Investigations\: clinical diagnosis; Auspitz sign, Psoriasis Area and Severity Index (PASI), skin biopsy if unclear, additional
tests for systemic symptoms.
Management\: avoid exacerbating factors, smoking cessation, reduce alcohol; topical therapies (emollients, corticosteroids,
tar preparations, calcipotriol); systemic therapies (methotrexate, acitretin, cyclosporin, biologics); phototherapy (narrowband
UVB).
Complications\: lifelong condition with resistant treatment; impaired quality of life, psychosocial burden, anxiety,
depression; severe forms can be fatal.
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A comprehensive topic overview

Introduction

Psoriasis is a chronic in
severity from a few isolated plaques to widespread in
Psoriasis a
equally a
It is commonest among Caucasian patients but may a
onset at approximately 15-25 and 50-60 years of age.
1

Aetiology

Development of psoriasis is complex, in
third of patients will have a family history of the condition.
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Inheritance is thought to be polygenic, with activation occurring when environmental factors are present. Although there
are many contributing factors, there is no clear trigger in most cases of psoriasis.
The underlying pathophysiology of psoriasis is autoimmune and T-cell mediated. It is thought that T-cells are
inappropriately induced to produce cytokines that stimulate in
keratinocyte proliferation (leading to scale as the stratum corneum is shed from the skin).
2

Risk factors

Precipitating factors

Psoriasis may be precipitated by infections, particularly streptococcal (associated with guttate psoriasis), or hormonal
changes, such as in the postpartum period.
Initiation, withdrawal or change in dose of some medications may also trigger or exacerbate symptoms, including lithium,
chloroquine and derivatives, and steroids (both systemic and potent topical forms).

Exacerbating factors

Psoriasis may be exacerbated by trauma due to cuts, abrasions or sunburn, which may precipitate the spread of plaques to
previously una
Smoking and alcohol and some medications may worsen symptoms. Psychological stress is widely believed to
exacerbate symptoms of psoriasis, although robust evidence supporting this is lacking.
3

Relieving factors

Sunlight is a relieving factor for most patients, with symptoms generally improving in summer and worsening in winter.
However, for a small number of patients (~10%) sunlight is an exacerbating factor.

Clinical features

History

Typical symptoms of psoriasis include\:
Pruritic lesions (generally mild although can be severe)
Pain or a burning sensation around the lesions (less common)
Joint pain and sti
Other important areas to cover in the history include\:
Family history\: many patients will have a family history of psoriasis.

Clinical examination

Typically, psoriatic lesions are\:
Well-demarcated, erythematous (reddened) plaques (areas of thickened skin)
Associated with an overlying scale (
and moist
Generally symmetrically distributed, most commonly located on the scalp, elbows and knees
Typically discrete, but may coalesce, leading to large a
Nail changes are seen in approximately 50% of patients, including pitting, onycholysis (distal separation of the nail from the
nail bed), yellowing and ridging (
Nail changes are generally associated with more severe disease and a greater burden of non-dermatological features.
Representative images in diverse skin types
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Due to copyright and image reproduction rules, we are only able to directly include images with particular licensing.
Unfortunately, the vast majority of images of dermatological conditions available under this licence are of patients
with fair skin tones.
Below are some representative images that we are not able to reproduce in this article directly\:
Guttate psoriasis on the neck and jaw of an African American child
Psoriatic plaques on the arms of a child (ethnicity unspeci

Clinical presentations

Psoriasis can be classi
described below, including seborrhoeic psoriasis, pustular psoriasis and palmar-plantar psoriasis.
Chronic plaque psoriasis is the most common presentation of psoriasis, with typical clinical features as described above.
May be further described as large (>3cm, often earlier onset) plaque or small plaque (\<3cm, often later onset) psoriasis.
Plaque psoriasis accounts for approximately 90% of cases of psoriasis.
6
Guttate psoriasis is characterised by multiple small, scaly plaques distributed across the trunk and limbs, which may
resemble raindrops (
responds well to treatment and may clear spontaneously in a matter of months.
Figure 3.Guttate psoriasis in a 9-year-old girl.
7
Erythrodermic psoriasis is a rare but severe form of psoriasis, which can occur acutely as the
or may evolve chronically from pre-existing psoriasis. Widespread in
resulting in dehydration, electrolyte disturbances, peripheral oedema, and rarely hypothermia or heart failure.
Erythrodermic psoriasis requires hospital admission for inpatient management.

Associated conditions

Psoriatic arthritis is a seronegative in
majority of cases, the rash precedes the arthropathy. Psoriatic arthritis can present as isolated arthritis of the distal
interphalangeal joints, oligoarthritis (predominantly large joint), polyarthritis, spondylitis or arthritis mutilans (severe
deformity with joint destruction).
8
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Figure 4.Severe psoriatic arthritis, with bone resorption and deformity.
9
In
colitis among patients with psoriasis is 2.5 and 1.7 respectively.
10
Other cutaneous manifestations of IBD include pyoderma gangrenosum, erythema nodosum and erythema multiforme, as
well as granulomatous plaques.
Uveitis (in
Metabolic syndrome refers to abdominal obesity, hypertension, dyslipidaemia and insulin resistance, and is associated
with psoriasis. There is some evidence additional to suggest that psoriasis is an independent risk factor for cardiovascular
disease.
11

Di

Alternate diagnosis Similarities Di
Pityriasis ruba pilaris
A group of rare
dermatological
conditions of unknown
aetiology
Presents with
erythematous plaques
with overlying scale
Scale tends to be
yellowish
Generally less
responsive to treatment
than psoriasis, though
may remit spontaneously

Investigations

Psoriasis is diagnosed clinically. Clinical tests include Auspitz sign, where gentle scraping and removal of scale causes
pinpoint capillary bleeding (although this is not a sensitive or speci
clinical tool that can be used to assess severity.
12
If the diagnosis is unclear, a skin biopsy can be performed. Additional investigations will be required if a patient with
psoriasis has systemic symptoms, including erythrodermic psoriasis.
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Management

Many patients with psoriasis will bene
exacerbating factors, smoking cessation, reducing alcohol consumption, and maintaining optimal weight.

Topical therapies

Moisturising emollients are recommended as regular therapy for all patients. Topical corticosteroids are the most
commonly prescribed therapy. Strength can be varied according to severity (plaque thickness) and skin sensitivity, and
pulse or continuous treatments may be used.
Tar preparations, most commonly liquor picis carbonis (LPC, coal tar) are anti-in
frequently combined with keratolytics (such as salicylic acid) to lift scale. Tar preparations are the preferred treatment for
trunk and limb psoriasis.
Calcipotriol is a vitamin D analogue and has an antiproliferative e
corticosteroids as an alternative topical therapy.

Systemic therapies

Methotrexate is frequently used as an oral therapy for severe unresponsive psoriasis, due to its e
cell proliferation. It is e
liver dysfunction and pulmonary
Acitretin is an oral retinoid that is anti-in
e
teratogen.
Cyclosporin is highly e
side e
psoriasis frequently recurs quickly after cessation of treatment.
Biologic therapies may be used in patients with treatment-resistant psoriasis (mostly restricted to severe disease due to
the expense associated with biologic agents). They may also be e
Treatment targets include TNFα (in
13

Other therapies

Psoriasis often responds well to narrowband UVB phototherapy, which down-regulates the immune and in
pathways of the skin. This is the phototherapy of choice for plaque psoriasis, but other forms of phototherapy may be used
for di
14

Complications

For most patients, particularly those with chronic plaque disease, psoriasis is a lifelong condition. The clinical course is
di
presence of plaques and associated symptoms, and side e
Additionally, it can be associated with a signi
depression.
Flares of severe forms of the condition, including pustular and erythrodermic psoriasis, can rarely be fatal, but direct
disease-related mortality is generally low.

References

DermNet NZ. P s o r i a s i s . 2014. Available from\: [LINK].
British Association of Dermatologists. H a n d b o o k f o r M e d i c a l S t u d e n t s a n d J u n i o r D o c t o r s . 2020. Available from\: [LINK].
Snast et al. P s y c h o l o g i c a l s t r e s s a n d p s o r i a s i s . 2018. Available from\: [LINK].
https\://app.geekymedics.com/notebook/2598/ 5/611/14/24, 10\:48 AM Psoriasis
James Heilman, MD. Adapted by Geeky Medics. P s o r i a s i s p l a q u e . Licence\: [CC BY-SA]. Available from\: [LINK].
Seenms. N a i l o f a p a t i e n t w i t h p s o r i a s i s , d e m o n s t r a t i n g p i t t i n g . Licence\: [CC BY-SA]. Available from\: [LINK].
Patient.info. C h r o n i c P l a q u e P s o r i a s i s . 2020. Available from\: [LINK].
Gzzz. G u t t a t e p s o r i a s i s i n a 9 y e a r o l d g i r l . Licence\: [CC BY-SA]. Available from\: [LINK].
Dhir et al. P s o r i a t i c a r t h r i t i s . 2013. Available from\: [LINK].
James [LINK].
Heilman, MD. S e v e r e p s o r i a t i c a r t h r i t i s , w i t h b o n e r e s o r p t i o n a n d d e f o r m i t y . Licence\: [CC BY-SA]. Available Yu et Jindal al. et A s s o c i a t i o n o f p s o r i a s i s w i t h i n LINK].
from\: [LINK].
DermNet NZ. P A S I s c o r e . 2009. Available from\: [LINK].
eTG Complete. P s o r i a s i s . 2015. Available from\: [LINK].
NICE. P s o r i a s i s a s s e s s m e n t a n d m a n a g e m e n t . 2017. Available from\: [LINK].
from\:

Reviewer

Consultant Dermatologist

Related notes

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Erythema Multiforme

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Contents

Introduction
Aetiology
Risk factors
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