*Comparative clinical significance is unknown.
Despite a widely held misconception that plaque psoriasis is less serious than other illnesses, it can impose a burden of visible symptoms that can be quite severe.2
Patients may understandably feel self-conscious or embarrassed about their disease. And the more severe their symptoms, the more impact on quality of life they may have — especially if plaques occur on highly visible or often-used areas.2,6
Based on ~1.7% prevalence (derived from UK data), plaque psoriasis is estimated to affect more than 500,000 Canadians.2
Of note, the Canadian Guidelines for the Management of Plaque Psoriasis (2009) suggests psoriasis is almost certainly undertreated in Canada as it is in other countries around the world. In fact, some severely affected patients may not be receiving any therapy whatsoever.2
Plaque psoriasis is the most common form of the disease and is present in roughly 90% of psoriasis patients2
A wide variety of putative triggers may worsen the disease, including physical trauma to the skin, cold weather, emotional stress, streptococcal throat infection, smoking, alcohol intake, postpartum hormonal changes, and certain drugs.2
The understanding of psoriasis continues to evolve. Whereas it was previously thought to be a Th1-mediated disease, Th17 cells are now seen to play a pivotal role. This suggests interleukin (IL)-17-producing dermal γδT cells likely play a vital role in pathogenesis.3
Pathway to plaques3,5
It has been proposed that plaque psoriasis is first triggered by foreign antigens that activate antigen-presenting cells (APCs). From there:
- APCs release proinflammatory cytokines which activate dermal γδT cells and other IL-17 producing cells
- IL-17, IL-22 and TNFα induce keratinocyte hyperproliferation, leading to chemokine release and immune effector cell recruitment
- Immune effector cells add to the proinflammatory response, resulting in an amplified positive feedback loop that leads to psoriatic plaques
TNF=tumour necrosis factor
Patients should know plaque psoriasis is not contagious and that they cannot pass it on to others4
Three histological hallmarks2
Extravagant growth of poorly
Presence of prominent,
dilated dermal blood vessels
Inflammatory infiltrate featuring
T cells, neutrophils, and macrophages
Plaque psoriasis is the most common form of the disease and is present in roughly 90% of psoriasis patients. It is characterized by red, scaly, discoid lesions called plaques, which are ≥0.5 cm in diameter.2
Plaques may occur as single lesions at predisposed sites (ex. knees, elbows) or as generalized disease across wider areas of the body. There is a sharp demarcation between the plaque and surrounding normal skin.2
Plaque psoriasis can be further classified according to specific anatomical sites and phenotypic variations.2
How severe is it?
While various tools are used to quantify disease severity in clinical trials,
Canadian guidelines recommend a more clinically minded scale.2
Mild: Up to 5% Body Surface Area (BSA)*
Minimal impact on the patient’s QoL; patient can achieve an acceptable level of symptomatic control by routine skin care measures and/or topical therapy
Cannot/would not be expected to be acceptably controlled by routine skin care measures, and/or a disease that significantly affects QoL due to extent, physical discomfort, or plaque location
Severe: ≥10% BSA†
Cannot/would not be expected to be satisfactorily controlled by topical therapy; causes severe degradation of the patient’s QoL
*Upper limit for “mild” disease suggested by the US National Psoriasis Foundation.
†Some clinical trials define “severe” disease as ≥20% BSA.
Estimating BSA: 1% BSA is roughly 1 palm-sized area (patient’s flat hand, thumb/fingers included)3
According to Canadian guidelines, patients who respond to first- or second-line therapy can be safely managed by their primary care providers. Referrals to a specialist should be considered when disease is extensive, distressing, or unresponsive, or where the patient requires in-depth counselling or education outside the scope of a primary care practice.2
Patients should be encouraged to make lifestyle changes (ex. stop smoking) and to avoid suspected triggering factors.
Heads-up: The scalp is the area most commonly affected by plaque psoriasis and where the disease first presents in many patients2
Enstilar® Safety Information
Indication and Clinical Use:
Enstilar® is indicated for the topical treatment of psoriasis vulgaris in adults for up to 4 weeks.
The use in pediatrics (<18 years of age) is not recommended as safety and efficacy have not been established in this population.
● Disorders of calcium metabolism
● Viral skin lesions; fungal, bacterial, parasitic skin infections; skin manifestations related to tuberculosis
● Perioral dermatitis, atrophic skin, striae atrophicae, fragility of skin veins, ichthyosis, acne vulgaris, acne rosacea, rosacea, ulcers and wounds
● Erythrodermic and pustular psoriasis
Relevant warnings and precautions:
● Long-term or concomitant corticosteroid use
● Use with ultraviolet radiation
● Avoid use on broken skin, on mucous membranes, in skin folds, or under occlusive dressing
● Hypercalcemia and hypercalciuria
● Hepatic or renal impairment
● Avoid ophthalmic use
● Avoid use on face, axillae, flexures, groin, or genitals
● Use caution in pregnant patients
● Avoid use on breast if breastfeeding
● Use in children <18 years of age or the elderly ≥65 years of age
For more information:
Please consult the Product Monograph at https://health-products.canada.ca/dpd-bdpp/index-eng.jsp for important information relating to adverse reactions, drug interactions, and dosing information, which have not been discussed in this piece. The Product Monograph is also available by calling LEO Pharma Medical Information at 1-800-263-4218.
© 2020 LEO Pharma Inc. All rights reserved.
® Registered trademark of LEO Pharma A/S used under license
and distributed by LEO Pharma Inc.
- IQVIA GPM TRX Audit. April 2020.
- Canadian Psoriasis Guidelines Committee. Canadian guidelines for the management of plaque psoriasis. 2009:1-109.
- 2016 Addendum to the Canadian Guidelines for the Management of Plaque Psoriasis 2009. J Cutan Med Surg 2016;20(5):375-431.
- Canadian Dermatology Association. Common Questions about Psoriasis. Available at: https://dermatology.ca/public-patients/skin/psoriasis/. Accessed August 14, 2019.
- Lovato P, Norsgaard H, Tokura Y, Røpke MA. Calcipotriol and betamethasone dipropionate exert additive inhibitory effects on the cytokine expression of inflammatory dendritic cell-Th17 cell axis in psoriasis. J Dermatol Sci 2016;81(3):153-64.
- Cardiff School of Medicine. Dermatology Quality of Life Index (DLQI). March 4, 2019. Available at: https://www.cardiff.ac.uk/medicine/resources/quality-of-life-questionnaires/dermatology-life-quality-index. Accessed Nov 5, 2019.