Eczema (Atopic Dermatitis) ICD-10: L20.9

Chronic inflammatory skin disease / Atopic condition

Often searched as: itchy dry skin patches, red itchy rash that comes back, dry flaky skin on elbows and knees, eczema on baby, skin that cracks and bleeds, itchy rash behind knees, rash on inner arms, chronic itchy skin…

Clinical urgency level

lowmediumhigh

Systems Affected

skinimmune system

Severity Levels

mild

Localized dry, itchy patches affecting less than 10% of body surface, manageable with emollients and occasional mild topical corticosteroids.

moderate

Widespread patches with significant itching, sleep disruption, and impact on daily activities — requires prescription topical treatments and possibly phototherapy.

severe

Extensive, persistent eczema covering large body areas, severe itch, sleep loss, secondary infections, and major quality-of-life impairment — may require systemic immunosuppressants or biologics (dupilumab).

Red Flags

Signs of skin infection in eczema patches: increased warmth, oozing yellow crust, fever (possible impetigo or cellulitis)
Sudden widespread worsening of eczema with fever and malaise (eczema herpeticum — a medical emergency caused by herpes virus on eczema skin)
Severe itching causing open wounds, sleep deprivation, or inability to work or attend school
Eczema not responding to prescribed treatment after 2–4 weeks
New areas of skin thickening (lichenification) spreading rapidly
Eczema in a young infant covering large body areas — needs urgent pediatric dermatology referral

Clinical Presentation

Atopic dermatitis (eczema) — red, dry, scaly patches in the elbow crease

Source: Wikimedia Commons (CC BY-SA 3.0 )

Eczema on the hands — dry, cracked, inflamed skin

Source: Wikimedia Commons (CC BY-SA 3.0 )

When to See a Doctor

See a doctor if eczema is causing significant itch, sleep disruption, or skin infections. Seek emergency care immediately if a widespread painful eczema flare is accompanied by fever and blisters — this may be eczema herpeticum, a serious complication. Infants with severe or widespread eczema should be evaluated promptly.

Differential Diagnosis

Contact dermatitis (allergic or irritant — triggered by specific substance)
Psoriasis (well-defined silvery plaques, different distribution)
Seborrheic dermatitis (oily, scaly — scalp, face, chest)
Tinea corporis (ringworm — circular, fungal)
Scabies (intense itch, burrows, often in web spaces)
Nummular eczema (coin-shaped patches)
Cutaneous T-cell lymphoma (in adults with chronic eczema-like rash not responding to treatment)

Comorbidities

Allergic rhinitis (hay fever) — part of the atopic triad
Asthma — part of the atopic triad
Food allergies (especially in children with severe eczema)
Sleep disturbances and chronic fatigue
Depression and anxiety
Skin infections (Staphylococcus aureus colonization, eczema herpeticum)

Prognosis

Many children with eczema improve significantly or grow out of it by adolescence — approximately 60–70% see substantial improvement. In adults, eczema tends to be more persistent and chronic. With proper management (emollients, topical corticosteroids, trigger avoidance), most patients achieve good control. Biologic therapy with dupilumab (Dupixent), approved for moderate-to-severe cases, has transformed outcomes for patients who previously had limited options. There is no cure, but long-term remission is achievable.

Detailed Overview

Causes, Symptoms, and When to Take Action Atopic dermatitis (eczema) is one of the most common chronic inflammatory skin diseases. It often begins in childhood but may persist into adulthood. How It Looks Texture: Dry, itchy skin; may have patches that are scaly, oozing, or crusted Color: Red to pink in lighter skin tones; darker or brownish in more pigmented skin Shape: Eczematous patches that may become thickened (lichenified) from scratching Location: Commonly on the face, neck, inner elbows, behind knees, and on hands Why Does It Appear? Genetic predisposition plays a role, including mutations that impair skin barrier function Skin barrier dysfunction leads to water loss and increased sensitivity to environmental irritants Immune dysregulation contributes to inflammation and itch Altered skin microbiome, including colonization by certain bacteria, may worsen the condition Should You Be Concerned? While eczema is not dangerous, it can significantly impact quality of life. You should seek medical advice if: Itching is severe or persistent Skin becomes infected, or there are signs of secondary infection Lesions are widespread, persist long term, or interfere with sleep or daily activity Can You Prevent It? Complete prevention is not always possible, but risk and severity of flares may be reduced by: Maintaining skin hydration (moisturizing regularly) Minimizing exposure to known irritants (such as harsh soaps, certain fabrics, or allergens) Managing environmental triggers (dry air, extreme temperatures) 👉 How Piel AI Can Help Piel AI allows you to monitor changes in your skin over time via regular images. While not diagnostic, it helps you notice new or worsening patches and supports informed discussions with healthcare providers. Summary Eczema (atopic dermatitis) is a chronic, relapsing inflammatory skin disease often starting in childhood. Key features are itchy, dry skin with red or discolored patches. Genetic, barrier, immune, and microbiome factors contribute. Though benign, it can reduce life quality, especially when severe. Good skin care, avoiding irritants, and monitoring are central.

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