Psoriasis Vulgaris (ICD-10: L40) ⚠️

Psoriasis Vulgaris (Plaque Psoriasis): Chronic Inflammatory Skin Disease

Overview

Psoriasis vulgaris, also known as chronic plaque psoriasis or chronic stationary psoriasis, is the most common form of psoriasis and accounts for up to 90% of cases. It is a chronic, immune-mediated inflammatory skin disorder characterized by the presence of well-defined, red, scaly plaques that can affect various parts of the body. These plaques often have a silvery-white surface due to hyperproliferation and defective maturation of keratinocytes.

Although not life-threatening, psoriasis significantly impairs quality of life due to its visible symptoms, pruritus, and potential systemic associations. It often follows a relapsing-remitting course and may be triggered or exacerbated by a variety of environmental and internal factors.

Epidemiology

Psoriasis affects approximately 1–2% of the population worldwide and occurs with equal frequency in men and women. While it can present at any age, two peaks are observed:

• Type I (early-onset): Appears before the age of 40, usually between 20 and 30 years; often associated with a familial history and more severe disease;
• Type II (late-onset): Appears after the age of 50 and is generally not hereditary.

Etiology and Triggering Factors

Psoriasis has a multifactorial origin, with contributions from genetic, environmental, and immunological mechanisms. Psoriasis is driven by genetic susceptibility and immune-mediated inflammation; a trigger may precipitate a first episode or set off a flare, but one is not required and often cannot be identified at all.

Key factors include:

• Genetic susceptibility: Polygenic inheritance; HLA-Cw6 gene is strongly associated with Type I psoriasis;
• Immune dysfunction: Activation of Th1 and Th17 immune responses, leading to cytokine overproduction (IL-17, TNF-α);
• Physical trauma (Koebner phenomenon);
• Infections: Particularly streptococcal infections (in guttate psoriasis), and upper respiratory tract infections;
• Drugs: Beta-blockers, lithium, NSAIDs, antimalarials, interferons, and withdrawal of systemic corticosteroids;
• Alcohol and tobacco use;
• Obesity and metabolic syndrome;
• Psychological stress;
• Climatic factors: Cold and dry environments may worsen symptoms.

Clinical Features

Psoriasis vulgaris typically presents with erythematous plaques covered by thick, white or silvery scales. The lesions are sharply demarcated, elevated, and may vary in size and distribution.

Common sites of involvement:

• Extensor surfaces of the elbows and knees;
• Scalp (including hairline and behind the ears);
• Trunk (especially lower back and umbilical region);
• Face (including eyelids and auditory canal);
• Palms and soles;
• Genital area;
• Nails (psoriatic onychodystrophy): Pitting, onycholysis, subungual hyperkeratosis, dystrophic thickening.

Pruritus is reported in approximately 60% of patients and may range from mild to severe. During exacerbations, lesions may multiply, enlarge, and become more inflamed. Periods of remission may last weeks to months or longer, depending on individual disease control.

Diagnostics

The diagnosis of psoriasis vulgaris is primarily clinical. A dermatologist can typically recognize the condition based on the characteristic appearance and distribution of lesions.

Diagnostic steps include:

• Physical examination: Identification of sharply demarcated plaques with silvery scaling, especially in typical areas (elbows, knees, scalp);
• The scraping signs — scales lifting in layers, a shiny red film beneath them, then pinpoint bleeding — are supportive, not required. They are not specific to psoriasis, and the diagnosis does not depend on eliciting them;
• Skin biopsy: Used in atypical cases or for confirmation. Histology reveals acanthosis, parakeratosis, Munro abscesses, and elongated rete ridges;
• Assessment of severity: Judged on the body surface area involved, the sites affected — scalp, face, hands, feet, nails and genitals count for more than their area suggests — symptoms, the effect on daily life and work, and whether there is joint involvement. The PASI score is a standardised research instrument used mainly in clinical trials, and a single number does not decide treatment.

Differential Diagnosis

Psoriasis vulgaris may mimic or overlap with other inflammatory dermatoses. Differential diagnosis should consider:

• Lichen planus;
• Atopic dermatitis;
• Chronic eczema;
• Pityriasis rubra pilaris;
• Pink lichen (pityriasis rosea);
• Seborrheic dermatitis (especially on scalp);
• Drug-induced dermatoses (e.g., lithium or antimalarial reactions);
• Cutaneous T-cell lymphoma (early mycosis fungoides);
• Ichthyosis, particularly in widespread scaling cases.

Treatment

The main goal of psoriasis treatment is to control symptoms, reduce inflammation, normalize keratinocyte turnover, and improve the patient’s quality of life. Treatment is guided by the extent of skin involvement, severity of symptoms, and presence of comorbidities.

Topical therapy — for limited disease, and alongside other treatment:

• Keratolytic agents: Urea, salicylic acid, and lactic acid to remove scaling;
• Topical corticosteroids: Low to high potency depending on location;
• Vitamin D analogs (e.g., calcipotriol): Normalize epidermal proliferation;
• Calcineurin inhibitors: Useful on sensitive areas (face, groin);
• Topical retinoids: Tazarotene for plaque reduction.

Phototherapy — for widespread disease that topical treatment cannot cover:

• Narrowband UVB is the usual choice; PUVA is reserved for selected cases. Both are given as a course of hospital or clinic visits, which is often what decides whether they are practical.

Conventional systemic therapy:

• Methotrexate: Long-established, and useful where psoriatic arthritis accompanies the skin disease;
• Acitretin: An oral retinoid, with strict precautions in anyone who could become pregnant;
• Ciclosporin: Effective and fast-acting, but limited by renal and blood-pressure effects to shorter courses;
• Fumaric acid esters, where licensed.

Biologic therapy:

• Targeted agents including TNF-α inhibitors (adalimumab, etanercept), IL-12/23 inhibitors (ustekinumab), IL-17 inhibitors (secukinumab) and PDE-4 inhibitors (apremilast). These are considered where disease is severe or has not responded to conventional systemic treatment, and the choice takes account of psoriatic arthritis, other illnesses and pregnancy plans. Licensing and availability differ considerably between countries, and local guidance applies.

Which step a patient starts on depends on how much skin is involved, which sites, how much the disease affects their life, whether the joints are involved and what other conditions they have — not on a severity score alone.

Complications

Psoriasis is not confined to the skin. It is associated with the conditions below, and these associations are not limited to severe or long-standing disease — they are worth asking about from the start:

• Cardiovascular disease: Increased risk of hypertension, ischemic heart disease, and stroke;
• Metabolic syndrome: Obesity, insulin resistance, and dyslipidemia are more common in patients with moderate to severe psoriasis;
• Psoriatic arthritis: Joint pain, swelling and progressive joint damage. Joint pain, swelling, or morning stiffness lasting more than about thirty minutes should be assessed, whatever the extent of the skin disease, because early treatment protects the joints;
• Psychosocial impact: Depression, anxiety, social isolation due to visible skin lesions and chronicity of the disease.

Prevention and Lifestyle Recommendations

Psoriasis cannot be completely prevented due to its genetic basis, but the frequency and severity of flares can be reduced through lifestyle and environmental modifications:

• Avoid known triggers (infections, trauma, smoking, stress, alcohol);
• Use emollients daily to maintain skin hydration and barrier function;
• Protect the skin from injury (Koebner phenomenon);
• Monitor for side effects if on long-term systemic therapy;
• Manage associated comorbidities, especially cardiovascular and metabolic risk factors;
• Follow regular dermatologic evaluations to monitor disease progression and response to treatment.

Conclusion

Psoriasis vulgaris is a common, chronic inflammatory skin disease with a significant impact on patients’ physical and emotional well-being. While it is currently incurable, advancements in topical, systemic, and biologic therapies allow for effective symptom control and improvement in quality of life.

Early diagnosis, personalized treatment, and patient education remain essential components of comprehensive care in patients with psoriasis vulgaris.