Psoriasis is defined as a systemic, immune-mediated inflammatory skin disease, which typically follows a chronic relapsing course (National Institute for Health and Care Excellence (NICE), 2017). The long-term nature of the condition can be very distressing for affected patients, impacting on quality of life. Psoriasis can develop at any age, affecting males and females equally, but is rare in children, and most cases present before the age of 35 years (Knott, 2021). There are several types of psoriasis, which can affect different sites of the body. Of these, chronic plaque psoriasis is the most common form, accounting for 80–90% of cases (Knott, 2021). Other types are shown in Table 1.
| Psoriasis type | Additional information |
|---|---|
| Localised pustular psoriasis | This is also called palmoplantar pustulosis and affects the palms and soles of the feet; it is the second most common form after chronic plaque psoriasis |
| Guttate psoriasis | This is often triggered by a bacterial infection and accounts for 2% of cases |
| Scalp psoriasis | This affects about half of people with chronic plaque psoriasis but can appear alone. Can affect just a few patches of the scalp or the whole scalp. Has the appearance of severe dandruff |
| Nail psoriasis | Affects approximately 50% of people with psoriasis but can also appear alone |
| Flexural psoriasis | Affects 3–7% of people with psoriasis and presents in the areas where there are skin folds (groin, armpits, and below the breasts) |
| Generalised pustular psoriasis | This is a rare type of psoriasis, affecting around 1% of cases Can flare quickly requiring admission to hospital. It has no association with localised pustular psoriasis |
| Erythrodermic psoriasis | This is a very rare form of psoriasis involving much of the skin surface. Urgent admission to hospital is needed. |
Source: McKechnie, 2023; NICE, 2023
Symptoms
Chronic plaque psoriasis, the most common variant, typically presents with well-demarcated circular to oval bright red/pink lesions (plaques) with an overlying white or silvery scale (Knott, 2021). Lesions often have a paler outer edge. The most frequent symptoms experienced are, according to the World Health Organization (2016):
- Scaling of the skin 92%
- Itchiness 72%
- Redness (erythema) 69%
- Fatigue 27%
- Swelling around the affected area 27%
- Burning sensation 20%
- Bleeding 20%
Localised pustular psoriasis (palmoplantar pustulosis) causes discoloured skin with pustules, which appear white or yellow in colour. Affected areas of skin cause itching, pain and fissuring, and treatments often take a long time to take effect (Micelli and Schnieder, 2023).
Guttate psoriasis is common in children and young adults and presents with small patches of scaly skin, which appear following an infection. The Koebner phenomenon (psoriasis appearing on previously healthy skin following an injury) may be a feature (Primary Care Dermatology Society (PCDS), 2021)
Flexural psoriasis presents with red inflamed skin but differs in that there is no scaling.
Triggers
Multiple factors have been studied to determine triggers that may cause onset of symptoms and/or trigger an exacerbation. It is known that what may affect one person may have no impact on another. Although poorly understood, genetics appears to play a role and approximately one-third of patients with psoriasis have a family member with the disease (Jones et al, 2023). Other possible factors are (Psoriasis Association, 2017; PCDS, 2021):
- Stress: this is thought to be strongly associated with psoriasis and is thought to act as a cause and a trigger for worsening the problem
- Alcohol: alcohol consumption in moderate to large amounts has been cited as an aggravating factor and may also make the condition more difficult to treat
- Obesity and smoking: both are associated with a poor response to treatment; smoking is associated with more severe disease and with pustular psoriasis
- Hormonal changes: psoriasis may appear at the time of puberty or the menopause. During pregnancy, psoriasis may improve and then can worsen again after the delivery
- HIV: psoriasis may be more severe in patients with HIV and more difficult to treat
- Medications: several medications are known to affect psoriasis. These include, antimalarial drugs (such as hydrochloroquine) and lithium. Beta blockers and nonsteroidal anti-inflammatory drugs (NSAIDS) may affect some patients, making their psoriasis worse
- Skin injury: psoriasis can sometimes develop at sites where there has been injury or trauma to the skin.
Aetiology
The process leading to the development of psoriasis is highly complex and is still not well understood. Current research suggests that the disease is induced by immune and environmental factors and controlled by interactions of multiple genes (Yin et al, 2015). The underlying pathophysiology of psoriasis is thought to be autoimmune and T-cell mediated (Thomson, 2024). Activated T cells are thought to infiltrate the skin leading to proliferation of keratinocytes and this dysregulation in keratinocyte turnover results in the formation of thick plaques (Nair and Badri, 2023). In addition, there is reduced secretion of lipids from epidermal cells, which results in the skin developing a scaly, flaky appearance. Psoriasis has a genetic component that is supported by patterns of familial aggregation. First and second-degree relatives of people with psoriasis have an increased incidence of developing psoriasis, and monozygotic (identical) twins have a two-to threefold increased risk compared with dizygotic (fraternal) twins (Rendon and Schakel, 2019).
Diagnosis
Diagnosis is usually made on clinical examination and further investigations are rarely needed unless the diagnosis is in doubt, when a biopsy may be helpful if there is a need to exclude a differential diagnosis. Several skin conditions have shared symptoms. More information on the most common differential diagnoses is shown in Table 2. When assessing patients, multimorbidity (defined as the presence of two or more chronic conditions) may be apparent. Individuals with psoriasis are more likely to suffer from obesity, cardiovascular disease, nonalcoholic fatty liver disease, diabetes, and metabolic syndrome than the general population, with rates being especially elevated in those with more severe psoriasis (Takeshita et al, 2017).
| Condition | Additional information |
|---|---|
| Seborrheic dermatitis | Facial psoriasis appearing in areas rich in sebaceous glands (scalp, face, ears). Psoriasis can be differentiated from seborrheic dermatitis as the plaques are thicker and have silvery white scales, whereas seborrheic dermatitis is characterised by patches surmounted by flaky greasy scales |
| Eczema | Affected areas are usually very itchy and acute lesions sho excoriations; crusting is common. May be differentiated psoriasis due to lack of sharp margination |
| Fungal skin infection | Lesions are typically solitary or unilateral and asymmetrical with peripheral scaling |
| Lichen planus | Can affect several areas of the body and presents as shiny papules varying in size. This can be differentiated from psoriasis by the presence of fine white lines (Wickham striae) often seen on the papules |
Source: Gisondi et al, 2020
Treatment
There is no cure for psoriasis and the aim of treatment is therefore to minimise symptoms and improve quality of life. Topical treatment is recommended as first line and patients may need to try several options before finding one that suits them, and will often need repeated courses when the problem flares.
Emollients
These are an essential part of the treatment plan and help to relieve itching and remove scales by softening the skin. They are available in several forms and, again, patients may try more than one before finding one that works for them. More information is given in Table 3.
| Preparation | Advantages | Limitations | Additional information |
|---|---|---|---|
| Ointment | Many products are preservative free and have a hydrating effect | Patient may find the greasiness unpleasant, which may affect correct use | Helpful on areas where the skin is thick with scaly plaques, but should be avoided on hairy areas of skin |
| Cream | Spreads more easily and much less greasy than ointments so patients may find more pleasant to use | Less efficacy and skin penetration when compared with ointments | Suitable for use at any site, including hairy areas |
| Lotion | Very easy to apply and not greasy, may be more acceptable to patients; Can have a cooling effect on the skin | There is very limited or no hydration with these products; no occlusive effect | Suitable for hairy areas but not the best option for the treatment of thick scaly plaques at other sites |
| Gel, water, or lipid based | Same advantages as lotions | Same limitations as lotions | Suitable for use at any site, including hairy areas |
| Aerosol foam, emollient based or hydroalcoholic | These are acceptable to patients as they are easy to apply, spread easily and some products offer skin hydration. Often preservative free | If the product is hydroalcoholic there is minimal occlusion or hydrating effect. If alcohol-based there is a risk of adverse effects, such as stinging, skin irritation and dryness. Products which are emollient based can be greasy | Most products are suitable for uses at all sitesd |
Source: Thaci et al, 2020
Vitamin D-based treatments (e.g., calcipotriol, calcitriol and tacalcitol)
These are available in varies forms (creams, lotions, gels, ointments, and scalp applications) and seem to achieve their effects by slowing the rate at which skin cells increase (McKechnie, 2023). Vitamin D based products are often combined with a steroid (eg, calcipotriol/betamethasone) but can cause skin irritation, soreness, and itching. An estimated 1 in 5 people are affected by adverse effects, but these generally improve following a break in treatment (McKechnie, 2023).
Dithranol and tar preparations were once used frequently, but their association with staining and skin irritation have made them less popular choices (Raharia et al, 2021).
Steroid and immunomodulator creams and ointments
Steroid creams are available in different strengths and the milder options can be used on the face. They are recommended for short term use only, because of the risk of skin atrophy with prolonged use. The frequency of use and tapering of topical corticosteroids is recommended once symptoms improve, symptoms often return weeks to months after discontinuation (Weigle and McBane, 2013).
New treatment options include medicated plasters containing betamethasone, which are useful for small joints (fingers and toes). These are for adults only.
Topical calcineurin inhibitors are second line options for moderate to severe eczema. The choices are:
- Tacrolimus 0.03% and 0.1 % ointments: Suitable for use in children 2 years of age and above and for adolescents and adults over 16 years or older (0.1%)
- Pimecrolimus 1% cream, licensed for children from the age of 3 months and beyond (NICE, 2024)
Both of the above work mainly by reducing inflammation through the suppression of T-lymphocyte responses (NICE, 2004).
Severe psoriasis and complications
Other treatment options may be needed for more severe or treatment-resistant psoriasis. These are shown in Table 4. Referral to secondary care may be needed if the psoriasis is severe and not responding to treatment, the diagnosis is uncertain, for any child presenting with symptoms or in the case of patients with suspected psoriatic arthritis. Psoriatic arthritis (swelling pain and joint stiffness) is an associated condition that can develop in patients with psoriasis. It is a poorly understood complication, estimated to affect approximately 1 in 10 people with psoriasis, often becoming problematic many years after the onset of the psoriasis (Tidy, 2024).
| Treatment type | Additional information | Mode of action |
|---|---|---|
| Phototherapy | Narrowband ultraviolet B (UVB) phototherapy is an option for patients with plaque or guttate psoriasis in whom topical treatment has been ineffective. This treatment is undertaken in the secondary care setting | Inhibits the proliferation of keratinocytes and induction of apoptosis (a process which eliminates unwanted cells) |
| Photochemotherapy combining psoralen with ultraviolet A (PUVA) | Given in specialist centres. Psoralen enhances the effects of UVA and can be administered by mouth or topically. Phototherapy now preferred to PUVA because of the increased risk of skin cancer with cumulative doses | Similar mode of action to phototherapy |
| Systemic treatments | ||
| Methotrexate | Prescribed in secondary care and may be an option if psoriasis has not improved with topical treatment or the psoriasis is extensive and is associated with severe distress | Achieves its effects by blocking processes which lead to inflammation. Inhibits an enzyme involved in the rapid growth of skin cells |
| Ciclosporin | Can be a first-line treatment if rapid or shortterm control is needed or if there is palmoplantar pustulosis. Also an option for both men and women considering conception | Works by suppressing the immune system to limit the overproduction of skin cells that occurs in patients with psoriasis |
| Acitretin | Used for pustular forms of psoriasis or if methotrexate or ciclosporin are unsuitable or have been ineffective | Similar mode of action to ciclosporin and achieves its effects by slowing the overproduction of skin cells |
| Apremilast or dimethyl fumarate | Used under specialist supervision in patients with severe plaque psoriasis | Works by inhibiting proinflammatory cytokines and is classed as small molecule drug because of its low molecular weight Mode of action of dimethyl fumarate is less well understood |
| Biological treatments | Biological agents (eg infliximab, adalimumab, etanercept, and interleukin antagonists) are prescribed and monitored in secondary care under specialist supervision | These drugs interfer with the immune mechanism associated with the developmen of psoriasis |
Source: National Institute for Health and Care Excellence, 2023
Impact on patients
Psoriasis is an unpleasant, distressing disease, which can present at any site and have variable degrees of severity. It often follows a relapsing and remitting course and because of its often-unsightly appearance it can be extremely upsetting for those affected. Anxiety and depression are possible and those affected may avoid interaction with others, leading to social isolation. Despite improvement in treatment there is no cure, and treatment aims to reduce the symptoms and address flare ups early when these occur. Some patients may be lucky and be free of symptoms for long periods, whereas others suffer more frequent exacerbations and more frequent treatment is needed. Some studies have reported that plaque psoriasis may clear altogether in 1 in 3 people over time (McKechnie, 2023). In recent years ongoing research and clinical trials have uncovered several promising new agents and others are in development. These therapies represent new mechanisms, pathways, and delivery systems, meaningfully broadening the spectrum of treatment choices for our patients (Pelet del Toro et al, 2023).
It is hoped that this article has given nurses and non-medical prescribers an overview and a better understanding of this unpleasant skin disease and given them more confidence in recognising and treating it with the aim of improving quality of life for all those affected.
KEY POINTS
- Psoriasis is a long-term chronic inflammatory condition
- The condition follows a relapsing and remitting course
- There are several forms, of which chronic plaque psoriasis is the most common
- Psoriasis can occur at any age but onset most frequently occurs between 20–30 years of age and 50–60
CPD reflective questions
- How confident do you feel in recognising psoriasis?
- Would you feel able to differentiate between psoriasis and other skin conditions such as eczema?
- How important is it for patients to recognise flare ups and seek help early?