Psoriasis Vulgaris (Plaque Psoriasis) ICD-10: L40.0

Chronic inflammatory skin disease / Immune-mediated

Often searched as: red scaly patches on elbows and knees, silvery scales on skin, thick white scales on scalp, psoriasis flare up, itchy red patches that come back, plaque psoriasis photos, psoriasis treatment, psoriasis on scalp…

Clinical urgency level

lowmediumhigh

Systems Affected

skinjoints (psoriatic arthritis — in ~30% of patients)cardiovascular system (increased risk)metabolic system

Severity Levels

mild

Less than 3% of body surface area affected, limited to elbows/knees/scalp — manageable with topical treatments (corticosteroids, vitamin D analogues).

moderate

3–10% of body surface area, cosmetically significant areas (face, hands, genitals), or significant impact on daily life — requires phototherapy or systemic treatment.

severe

More than 10% of body surface area, or any extent with joint involvement, or unresponsive to topical treatment — requires systemic agents or biologics.

Red Flags

Sudden widespread flare covering large body areas (possible erythrodermic psoriasis — emergency)
Joint pain, swelling, or morning stiffness alongside skin plaques (possible psoriatic arthritis — requires rheumatology referral)
Psoriasis on the face, hands, genitals, or nails causing significant functional impairment
Skin plaques that are rapidly thickening, ulcerating, or becoming very painful
Psoriasis not responding to any treatment after 3 months
New or worsening cardiovascular symptoms (psoriasis is an independent cardiovascular risk factor)

Clinical Presentation

Psoriasis vulgaris — well-defined erythematous plaques with silvery scale on the elbow

Source: Wikimedia Commons (CC BY-SA 3.0 )

Plaque psoriasis image gallery — DermNet NZ

View gallery on DermNet NZ (image gallery reference)

When to See a Doctor

See a dermatologist if you have scaly, red plaques that keep recurring or expanding, especially on visible areas like the face or hands. See a rheumatologist if joint pain develops — psoriatic arthritis can cause irreversible joint damage if untreated. Annual cardiovascular risk screening is recommended for moderate-to-severe psoriasis patients.

Differential Diagnosis

Seborrheic dermatitis (similar on scalp and face — less defined, greasier scale)
Eczema / atopic dermatitis (less defined borders, no silvery scale, very itchy)
Tinea corporis (ringworm — circular, responds to antifungal)
Pityriasis rubra pilaris (orange-red, follicular — islands of sparing)
Secondary syphilis (papular — serologic testing)
Bowen's disease (single, well-defined scaly patch — SCC in situ)

Comorbidities

Psoriatic arthritis (~30% of psoriasis patients)
Cardiovascular disease (increased risk — systemic inflammation)
Metabolic syndrome and type 2 diabetes
Inflammatory bowel disease (Crohn's, ulcerative colitis)
Depression and anxiety (significant psychological burden)
Obesity (worsens psoriasis severity and reduces treatment response)

Prognosis

Psoriasis vulgaris is a chronic, relapsing-remitting disease with no current cure, but highly manageable. Mild disease is well-controlled with topical treatments. Moderate-to-severe disease has been transformed by biologic therapies (anti-TNF, anti-IL-17, anti-IL-23) — PASI 90 or 100 responses (near-complete or complete skin clearance) are now achievable in the majority of patients on newer biologics. Early treatment of psoriatic arthritis prevents irreversible joint damage. Long-term cardiovascular risk management is important for overall health.

Detailed Overview

Causes, Symptoms, and When to Take Action Psoriasis vulgaris, also known as plaque psoriasis, is a chronic inflammatory skin condition that affects millions of people worldwide. It is characterized by recurring episodes of scaly, red, and thickened skin lesions that can vary in severity. How It Looks Texture: Raised, thickened plaques covered with silvery or white scales Color: Red or pink base beneath scaling Shape: Well-defined patches, often round or irregular Location: Commonly appears on elbows, knees, scalp, and lower back Why Does It Appear? Psoriasis vulgaris develops as a result of complex interactions between the immune system, genetics, and environmental triggers. Factors such as stress, skin injury, infections, and lifestyle habits may contribute to flare-ups. Should You Be Concerned? Although psoriasis is not life-threatening, it can significantly impact quality of life and may be associated with joint pain and systemic inflammation. Can You Prevent It? Psoriasis cannot be completely prevented, but flare-ups may be reduced by avoiding triggers, maintaining a healthy lifestyle, and monitoring skin changes. 👉 How Piel AI Can Help Piel AI allows you to track changes in skin lesions over time to help stay aware of flare-ups and provide information for your healthcare provider. Summary Psoriasis vulgaris is a chronic inflammatory skin disease marked by red, scaly plaques. It arises from immune, genetic, and environmental factors. While not life-threatening, it affects quality of life and may be linked to broader health concerns. Monitoring and preventive strategies help manage flare-ups.

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