L-17 Atopic Dermatitis (Eczema)

• Atopic Dermatitis also known as Eczema
• Atopic dermatitis is a chronic inflammatory skin disease known as "The itch that rashes".
• Atopic dermatitis rash Pruritic, Superficial, Chronic, Scaly, Excoriation
• Hallmark symptom is Pruritus (itching).
• Atopic Dermatitis is most common inflammatory skin disease in children and adults, affecting 15%-20% of children worldwide.
• Specifice etiology is unclear.
• It is usually not an allergy to one thing. It is a supersensitivity to triggers that are irritant in nature.

Risk Factors and Onset

• Risk factors include family history, genetics, and environment.
• Atopy denotes a form of allergy and the role of allergies is unclear in Atopic Dermatitis.
• Onset is commonly after 2 months of age; 85% of cases occur by age 1 and 95% by age 5. Onset after puberty = higher risk for life-long involvement.
• About 30% of cases may advance from childhood to adolescence.
• Age-related patterns include Infantile eczema, Childhood eczema, Adolescent/Adult eczema.
• Many pediatric patients "outgrow" Atopic dermatitis and the condition gets better over time.

Diagnosis and Development

• Diagnosis is based primarily on Clinical Manifestations.
• There is No definitive laboratory test to diagnose Atopic Dermatitis.
• Atopic Dermatitis generally improves with age; about 40% clear by age 3 and about 70% by puberty.
• About 50% to 80% of children with Atopic Dermatitis will develop another atopic disease.
• Atopic Dermatitis frequently relapses (flare-ups and remissions), but is not often predictable.
• It may have an adverse impact on quality of life and emotional health of children; interferes with sleep and school performance.

Complications

• A common complication is secondary skin infections (impetigo), most commonly caused by Staphylococcus aureus (>80%).
• It is 40% associated with food allergies (nature of association is unclear).
• It is rare in the diaper area; if eczema is seen in diaper area, it is suggestive of food allergies.
• Atopic Triad consists of Atopic Dermatitis, Asthma, and Allergic Rhinoconjunctivitis.
• Atopic March is a progression of allergic disorders as a patient develops multiple allergic conditions with age, including food allergies, allergic rhinitis, and asthma, with atopic dermatitis as the initial feature.

Clinical Profile

• History of pruritis is a hallmark.
• Family history of allergies is a factor.
• Appearance of lesions: scaly, dry, lichenified
• Distribution of rash: flexural vrs extensor
• Lesion onset and duration: childhood onset vrs adult onset
• Signs/Symptoms: pruritis; scratching; rubbing; irritation; erythema; papules; vesicles; lichenification; excoriation.

Pathogenesis

• Faulty epidermal barrier results in mutations + deficiency in filaggrin along with a decrease in ceramides and transdermal water loss.
• Immune dysregulation causes alterations in cutaneous innate + adaptive immunity.
• Defective neutrophil and monocyte chemotaxis with Abnormal T cell function.
• Type 2 Inflammation (80%): is an immune system overreaction to non-threats; involves Basophils, Mast cells + T-helper Type 2 cells that produce Type 2 Cytokines -> induce inflammation.
• Elevated immunoglobulin E (IgE) – in about 80% of cases.
• Family history of allergy is a factor (first-degree relative with asthma or allergic rhinitis)
• Environmental triggers include cold and dry weather, house dust mites, pet fur, pollen, molds, and food allergens (cows milk, peanuts, soya, wheat)

Infantile Eczema

• Eczema in infants usually has an onset at 2 months of age.
• Location: extensor surfaces of arms and legs; cheeks, forehead; scalp
• It spares moist folds of skin and diaper area typically.
• Intensely pruritic and irritable papules that unable to scratch effectively, scratching leads to persistent, erythematous, scaling, oozing, crusty plaques
• Infant often has a history of seborrheic dermatitis ("cradle cap"), scaly!

Childhood Eczema

• Childhood eczema occurs from 2 years to puberty/adolescence
• Usually flexural (antecubital and popliteal fossae); wrists; ankles; posterior neck.
• Facial presentation: periorbital and perioral
• May result in lichenification and pigmentary changes; follicular.
• Secondary bacterial infections may occur, with lymphadenopathy.

Adolescent/Adult Eczema

• Lichenification ("leathery appearance") is common.
• Rash distribution is predominantly flexural (antecubital and popliteal); dorsal aspects of hands and feet; face; nape of neck; lips.
• Follicular post-inflammatory hyperpigmentation is prominent at the adolescent stage.
• Keratosis pilaris ("goose-bump" feel to skin) common in adults

Pityriasis Alba Manifestation

• Pityriasis alba is superficial scaly macules (slight/yellowish hypopigmentation); patches over the cheeks and extensor surfaces; symmetrical distribution.
• It is a common feature of Atopic Dermatitis.

Allergic Shiners Manifestation

• Allergic shiners are darkened, mildly erythematous or tanned periorbital areas, bilaterally and symmetrically.
• It is typically a feature in Atopic Dermatitis.

Keratosis Pilaris Manifestation

• Keratosis pilaris represents a sparse or confluent distribution of follicular papules (grainy feel when rubbed lightly)
• It is often seen symmetrically on dorsal upper arms (extensor surfaces) or on the trunk.
• More common in adults and often symmetrical in distribution.

Lichenification Manifestation

• Lichenification is skin thickening and exaggeration of normal skin markings ("leathery patches")
• Seen at popliteal fossa and antecubital fossa (flexural surfaces) symmetrically.
• Is often a consequence of the "itch-scratch cycle" and is associated with subacute/chronic eczema.
• Hyperpigmentation is quite evident in patients with darker skin.
• Epidermis: abnormal accumulation of keratinocytes; (parakeratosis) + thickening of skin - leathery (acanthosis). Dermis: inflammatory cell infiltrates.

Nummular Eczema Manifestation

• Nummular eczema is dry “coin-lack" patches; sparsely distributed on extremities, and trunk with itchiness.

Dennie-Morgan Folds Manifestation

• Periorbital eczema.
• Dennie-Morgan folds = infraorbital folds in the skin below the eyelids.
• Varying severity, a mild form referred to as "Dennie's pleats"

Other Manifestations

• Atopic cheilitis (lip-smacking eczema) is perioral eczema.
• Thumb-sucking Eczema - eczematous with dryness, cracking, calluses.
• Hyerlinear palms
• Spares diaper area

Dyshidrotic Eczema Manifestation

• Dyshydrotic eczema is characterized by fluid-filled blisters appearing on the hands and fingers.
• It usually lasts about 3 weeks and is very dry and pruritic.
• Treatment: Corticosteroids, Phototherapy, and Moisturizers.
• The cause is unknown, although often associated with allergies and stress. Linked to Vit D deficiency.

Secondary bacterial infection

• Secondary bacterial infection (Impetigo) is the most common complication of Atopic dermatitis.
• Staphylococcus aureus is the most common cause of secondary bacterial infections in Atopic Dermatitis;
• Staphylococcus aureus produces toxins that trigger flare-ups.
• Impetigo can develop further into Cellulitis.

Secondary Viral Infection

• Eczema Herpeticum (Kaposi Varicelliform Eruption) is a secondary viral infection in Atopic Dermatitis,
• It is commonly caused by Herpes Simplex virus.
• The lesions are typically on the face, commonly occurs in infants.
• Note: This is different from Dermatitis herpetiformis, a rare persistent immunobullous disease associated with Gluten-sensitive enteropathy (Celiac Disease).

Major Diagnostic Criteria for Atopic Dermatitis

• There needs to be 3 major and 3 minor criteria
• Pruritis (persistent)
• Distribution (Flexural (adult)/Extensor + face (infant)
• Rash (chronic/relapsing)
• Atopy (Personal/Family history).
• Commonly referred to as Hanin and Rajka Criteria.

Minor Diagnostic Criteria

• Atopic facies: Pityriasis alba; facial erythema; allergic shiners; Dennie's pleats; Cheilitis; neck folds; recurrent conjunctivitis.
• Triggers: Foods; emotions; environment; skin irritants
• Complications: secondary skin infections; impaired cell-mediated immunity; skin test reactivity; Elevated IgE; Keratoconus (bulging of cornea); Cataracts
• Others: Early age of onset; Xerosis (dry skin); ichthyosis; hyperlinear palms; keratosis pilaris; hand/foot dermatitis; nipple eczema; white dermatographism; folliculitis.

Management

• Moisturizers like Eucerin, Cetaphil, Aquaphor
• Topical Corticosteroids such as Hydrocortisone, Fluticazone (Cutivate) vary in potencies.
• Topical Non-steroidal Immunomodulators such as Topical Tacrolimus (Protopic) and Pimecrolimus (Elidel) are reserved for > 2y.o.; if unresponsive to standard therapy.
• Antihistamines such as Hydroxyzine (Atarax) Citrazine (Zyrtec) and Loratidine (Claritin) are used for pruritis.
• Antibiotics such as Cephalexin (Keflex), Clindamycin or Doxycycline treat secondary bacterial infections.
• Systemic Immunosuppressants such as Cyclosporine are for severe refractory Atopic Dermatitis.
• Anticipatory Guidance (verbal advice) along with a Written Action Plan is key.
• Avoid Triggers
• Gentle/Sponge bathing (e.g. non-fragrant soaps) is useful.

Differential Diagnosis

• Atopic Dermatitis
• Scabies
• Varicella-Zoster (Chicken pox)
• Seborrheic dermatitis
• Allergic contact dermatitis
• Contact Irritant dermatitis
• Drug reaction
• Insect bite
• Impetigo
• Rhus dermatitis (Poison ivy)
• Xerosis
• Ichthyosis vulgaris
• Acrodermatitis enteropathica (Zinc deficiency)
• Dyshydrotic eczema
• Wiskott-Aldrich syndrome (rare; X-linked; Immunodeficiency, Eczema Thrombocytopenia)