plaque psoriasis

Plaque psoriasis is a chronic autoimmune skin condition that is caused by the rapid buildup of skin cells on the surface. Presentations include thick, raised, and scaly patches known as plaques. These plaques are typically red or pink in colour and can be covered with silvery-white scales. The condition most commonly affects the elbows, knees, scalp, lower back, and nails. Plaque psoriasis can cause itching, pain, and discomfort. The aim of treatment is to manage symptoms and reduce inflammation.

Epidemiology

In the US, approximately 2% of the population is affected by plaque psoriasis
Some ethnic minority populations have a very low prevalence of plaque psoriasis such as Japanese, aboriginal Australians and Indian located in South America [1]
Psoriasis affects 1.3-2.8% of the UK population
Long term plaque psoriasis is the most common types of psoriasis
According to NICE, 80-90% of people affected by psoriasis have it in plaque form [2]

Source: DermNetNZ.org

Plaque Psoriasis
Well bordered plaques with a silverly scale on the plaques

Source: DermNetNZ.org

Plaque Psoriasis
Thick silvery scale over the elbow

Causes [3]
- Immune system attacking healthy cells (auto-immune conditions)
- Inheritance from families
- Triggers that cause flare-ups:
- Injury to the skin
- Drinking excessive amounts of alcohol
- Smoking
- Stress
- Hormonal changes
- Throat infections
- HIV
- Medicines like lithium, ACE inhibitors etc

Pathophysiology [4]
- Medical students
  - The hallmark of psoriasis is sustained inflammation that leads to uncontrolled keratinocyte proliferation and dysfunctional differentiation.
  - The histology of the psoriatic plaque shows epidermal hyperplasia, which overlies inflammatory infiltrates composed of dermal dendritic cells, macrophages, T cells, and neutrophils
  - Neovascularization is also a prominent feature. The inflammatory pathways active in plaque psoriasis and the rest of the clinical variants overlap, but also display discrete differences
  - Disturbances in the innate and adaptive cutaneous immune responses are responsible for the development and sustainment of psoriatic inflammation
- Patients
  - The hallmark of psoriasis is sustained (continuous) inflammation that leads to uncontrolled keratinocyte (cells that produce keratin- which produces nails and skin) proliferation and dysfunctional differentiation.
  - The histology of the psoriatic plaque shows epidermal hyperplasia (skin tissue overproduction), which overlies inflammatory infiltrates composed of immune cells affecting the skin such as dendritic cells, macrophages, T cells, and neutrophils
  - Neovascularization is also a prominent feature. The inflammatory pathways active in plaque psoriasis and the rest of the clinical variants (different types of psoriasis) overlap, but also display discrete differences
  - Disturbances in the innate (naturally present in the body) and adaptive (triggered in response to re/infections) in the skin immune responses are responsible for the development and sustainment of inflammation seen within psoriasis

Plaque Psoriasis

Thick white scale developing on the legs

Risk factors [5]
- Tobacco
- Alcohol
- Obesity
- Infections (eg. streptococcus triggers guttate psoriasis)
- Drugs such as beta blockers and lithium
- Stress
- Weather (cold conditions)
- Koebner’s phenomenon- presense/ reproduction of skin lesions at the areas of injury

Presentations [6]
- Elevated patches and areas of skin
- Palpable lesions (can be touched)
- Large surface area
- Silver, thick and shiny scales are found on the patches
- Dark purple appearance of lesions on darker skin

Plaque psoriasis

Involvement of multiple areas of the skin with lesions clustered on or around the knee

Investigations [7]
- Clinical examination of appearance and history of symptoms, nail, joint problems and family history of psoriasis; as well as recent changes in life such as stress or illness
- Skin biopsy (sample taken from skin) to confirm a diagnosis of psoriasis

Differential diagnosis [8]
- Discoid eczema- inflammatory skin condition
- Tinea corporis- also known as ringworm
- Psoriasis rosea- tree distribution of plaques
- Seborrhoeic dermatitis- flaky skin found on the scalp, face and upper trunk
- Drug-induced psoriasis
- Follicular problems such as inflammation and psoriasis rubra pilaris which involves the follicles

Plaque psoriasis

Scaly, elevated lesions on the lower back and buttocks

Management [9]
- Medical students
  - Consider patient preferences, cosmetic and practical aspects of treatment, and the body surface area affected
  - Discuss the different formulations available.
    - An ointment is preferred for scaly plaques
    - Discuss referral for phototherapy or systemic therapy if patients are unlikely to respond adequately to topical therapy alone
  - Medications
    - After a new topical therapy is started, arrange to review adults in 4 weeks and children in 2 weeks to:
      - Assess the response to treatment, and how it has been tolerated
      - Review adherence to the treatment
      - Highlight the importance of a break between courses of potent and very potent corticosteroids
      - Identify the need for daily use of topical corticosteroids, which indicates that systemic therapy should be considered
      - Discuss treatment alternatives if the response has been unsatisfactory
    - If the response has been unsatisfactory, consider the following:
      - Difficulties with current therapy, such as tolerance, practical aspects of the application and cosmetic acceptability
      - Other reasons for non-adherence
      - Prescribing a different formulation
    - Review psoriasis patients at least annually to assess for adverse effects of steroid therapy, if:
      - An adult is using potent or very potent corticosteroids
      - A child using any form of corticosteroids
  - Other treatment types
    - Emollients
      - Recommend emollients to all patients with psoriasis. They improve dryness, scaling, and cracking and may have their own antiproliferative properties. They can be used with other treatments
      - Emollients may be all that is required to treat mild psoriasis.
      - Emollients are especially beneficial for psoriasis of the palms and soles
      - Ointments and thick creams are most effective, particularly when applied straight after a shower or bath
    - Soap substitute
      - A soap substitute such as aqueous cream can help improve symptoms.
    - Coal tar
      - Coal tar has anti-inflammatory and anti-scaling properties however it holds limitations such as irritation and staining of clothes
    - Dithranol
      - It is effective on large, thick plaques as ‘short-contact therapy’, where it is applied daily, initially with a contact time of 10 minutes which is steadily increased to 30 minutes over 7 days.
      - It can also be used for scalp psoriasis
    - Salicylic acid
      - A Keratolytic agent that reduces scaling and increases penetration of other topical treatments.
      - It can be prescribed in combination with a topical corticosteroid or emollient. It is often already present in coal tar formulations.
      - Salicylic acid is contraindicated in women who are pregnant
    - Calcipotriol
      - Calcipotriol is often used as first-line therapy for plaque psoriasis.
      - It is also available in combination with topical betamethasone dipropionate and is available as gel, ointment and foam formulations.
      - Calcipotriol may cause irritation when applied to sensitive sites (eg, the groin).
    - Corticosteroid
      - They have anti-inflammatory, anti-proliferative and immunosuppressive properties through their effect on gene transcription
        Prolonged potent or very potent corticosteroid use may result in:
        Permanent striae and/or skin atrophy
        Unstable psoriasis
        Adrenal suppression
        Paradoxical worsening of psoriasis
        Potent corticosteroids should not be used continuously at any site for more than 4 weeks without a break.
        Very potent corticosteroids should not be used for more than 4 weeks continuously.
        Offer an alternative topical treatment option during this time to maintain control of psoriasis if required (eg, calcipotriol or coal tar).
        Very potent corticosteroids are not suitable for children
      - Tazarotene
        Tazarotene is a topical retinoid
        It is best used in combination with topical corticosteroids
- Patients
  - Consider patient preferences, cosmetic and practical aspects of treatment, and the body surface area affected
  - Discuss the different formulations available.
    - An ointment is preferred for scaly plaques
    - Discuss referral for phototherapy (use of light) or systemic therapy (work throughout the whole body) if patients are unlikely to respond adequately to topical (applied to skin) therapy alone
  - Medications
    - After a new topical therapy is started, arrange to review adults in 4 weeks and children in 2 weeks to:
      - Assess the response to treatment, and how it has been tolerated
      - Review adherence to the treatment
      - Highlight the importance of a break between courses of potent and very potent corticosteroids
      - Identify the need for daily use of topical corticosteroids, which indicates that systemic therapy should be considered
      - Discuss treatment alternatives if the response has been unsatisfactory
    - If the response has been unsatisfactory, consider the following:
      - Difficulties with current therapy, such as tolerance, practical aspects of the application and cosmetic acceptability
      - Other reasons for non-adherence
      - Prescribing a different formulation
    - Review psoriasis patients at least annually to assess for adverse effects of steroid therapy, if:
      - An adult is using potent (strong/effective) or very potent corticosteroids
      - A child using any form of corticosteroids
  - Other treatment types
    - Emollients (moisturising treatment)
      - Recommend emollients to all patients with psoriasis. They improve dryness, scaling, and cracking and may have their own antiproliferative properties. They can be used with other treatments
      - Emollients may be all that is required to treat mild psoriasis.
      - Emollients are especially beneficial for psoriasis of the palms and soles
      - Ointments and thick creams are most effective, particularly when applied straight after a shower or bath
    - Soap substitute
      - A soap substitute such as aqueous (mixed with water) cream can help improve symptoms.
    - Coal tar
      - Coal tar has anti-inflammatory and anti-scaling properties however it holds limitations such as irritation and staining of clothes
    - Dithranol
      - It is effective on large, thick plaques as ‘short-contact therapy’, where it is applied daily, initially with a contact time of 10 minutes which is steadily increased to 30 minutes over 7 days.
      - It can also be used for scalp psoriasis
    - Salicylic acid
      - A Keratolytic (breaks down the outer layer of the skin) agent that reduces scaling and increases penetration of other topical treatments.
      - It can be prescribed in combination with a topical corticosteroid or emollient. It is often already present in coal tar formulations.
      - Salicylic acid is contraindicated in women who are pregnant
    - Calcipotriol
      - Calcipotriol is often used as first-line therapy for plaque psoriasis.
      - It is also available in combination with topical betamethasone dipropionate and is available as gel, ointment and foam formulations.
      - Calcipotriol may cause irritation when applied to sensitive sites (eg, the groin).
    - Corticosteroid
      - They have anti-inflammatory, anti-proliferative and immunosuppressive (suppresses the immune response) properties through their effect on gene transcription
        Prolonged potent or very potent corticosteroid use may result in:
        Permanent striae (lines formed) and/or skin atrophy (wasting)
        Unstable psoriasis
        Adrenal suppression (reduction in the hormone cortisol)
        Sometimes, a worsening of psoriasis
        Potent corticosteroids should not be used continuously at any site for more than 4 weeks without a break.
        Very potent corticosteroids should not be used for more than 4 weeks continuously.
        Offer an alternative topical treatment option during this time to maintain control of psoriasis if required (eg, calcipotriol or coal tar).
        Very potent corticosteroids are not suitable for children
      - Tazarotene
        Tazarotene is a topical retinoid
        It is best used in combination with topical corticosteroids.

Source: DermNetNZ.org

Plaque psoriasis
Yellow, thick plaques found on the knee

Source: DermNetNZ.org

Plaque psoriasis
Scaling on the ankle with redness and silvery flakes

Complications [2]
- Psychological impacts due to appearance
- Heart failure due to changes in blood flow
- Malabsorption- changes in intestinal function
- Hypothermia- increased heat loss from the body due to psoriasis
- Mild anaemia due to increased scaling
- Dehydration- increased water loss from the skin due to skin barrier dysfunction
- Complications to pregnancy with increased risk of miscarriages, preterm birth and low birthweight

Myths
- Psoriasis is contagious
- There is only one type of psoriasis
- It is a product of poor hygiene
- Psoriasis is the same as eczema
- Severity is determined by the amount of skin covered in plaques [10,11]
Questions to ask your doctor
- How did I get this form of psoriasis?
- Is there anything I can do to manage symptoms?
- Will be treatment change if I am on medications already?
- What are the possible side effects of treatment?
- How long does it take for treatment to be effective?
Support
- National Psoriasis Foundation
- British Skin Foundation
- Psoriasis and Psoriatic Arthritis Alliance