Atopic dermatitis

Also called atopic eczema, eczema

The itch that rashes: a chronic relapsing barrier-and-immune disease, usually beginning in childhood, tied to asthma and allergic rhinitis. Distribution shifts with age, face and extensors in infants, flexures later.

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How it looks

Ill-defined erythematous, scaly, excoriated patches and lichenified plaques symmetrically involving the antecubital and popliteal fossae.

Plaque Scale Excoriation Lichenification Erythema Fissure Crust Confluent Flexural

Rose is the lesion, grey the pattern the lesions make, green where on the body it lives.

Across skin tones

Follicular (papular) eczema and lichenification are more prominent presentations in deeply pigmented skin; erythema may be subtle while post-inflammatory hypo- and hyperpigmentation dominate the picture.

Don't miss

A sudden flare of painful punched-out vesicles and erosions in an atopic patient is eczema herpeticum, a dermatologic emergency, not a bad eczema day.

Symptoms & course

Intense itch, the defining symptom
Dry skin everywhere, not just the rash
Sleep disturbance from nocturnal scratching

Diagnostic approach

Clinical diagnosis
Swab crusted weeping areas if secondary infection suspected
No routine allergy testing for typical disease

Differential, and how to separate them

Contact dermatitis
Favours it: Sharp borders, shape matches an exposure
Against it: Lacks the flexural symmetry and atopic history
Scabies
Favours it: Burrows, finger-web involvement, itchy contacts
Against it: No burrows; distribution flexural rather than acral
Psoriasis
Favours it: Well-demarcated silvery plaques
Against it: Atopic plaques are ill-defined and dominated by itch

Management principles

Liberal emollients as the foundation
Topical corticosteroids matched to site and severity for flares
Address scratching, triggers, and secondary infection

Clinical pearl: Treat the itch and you treat the disease, most 'treatment failures' are under-treated itch and under-used emollients.

Clinical pearl: The Dennie–Morgan infraorbital fold and palmar hyperlinearity are quiet atopy clues on examination.

Keep going

Try the case: The itch that keeps coming back Compare with Psoriasis Back to the Atlas