Atopic Dermatitis Master Review

These vocabulary flashcards cover the definitions, nomenclature, pathogenesis, clinical features, and management strategies for Atopic Dermatitis as presented in the lecture notes.

Atopic Dermatitis (AD)

A common chronic inflammatory skin disease usually beginning in infancy or early childhood, characterized by intense pruritus and a chronically relapsing course.

Atopy

Meaning "strange" or "unusual," derived from the Greek word "atopos," historically used to describe the triad of atopic dermatitis, asthma, and allergic rhinitis.

Atopic March

The age-dependent sequence of atopic diseases appearing simultaneously or successively, moving from atopic dermatitis and food allergy in infants to asthma in older children and allergic rhinoconjunctivitis in adolescents.

WAO Atopy Definition

Links atopy tightly to the presence of allergen-specific $IgE$ antibodies in serum, documented by skin prick tests or fluorescence enzyme immunoassays.

Intrinsic AD

Formerly used to describe Non-$IgE$-associated or non-allergic dermatitis, which account for $20\%$–$30\%$ of atopic dermatitis phenotype patients.

TEWL

Transepidermal water loss; a measure of epidermal permeability barrier defect that correlates with disease severity in non-lesional skin.

Filaggrin ($FLG$)

A keratin filament-aggregating protein and major component of the stratum corneum; loss-of-function ($LOF$) variants in its gene are the strongest known genetic risk factor for atopic dermatitis.

Stratum Corneum Lipids

Determinants of epidermal permeability barrier function including composition, organization, and biochemical processing; their generation is negatively affected by Th2 cytokines and $Staphylococcus\,aureus$ colonization.

LEKTI

Lymphoepithelial Kazal-type trypsin inhibitor, encoded by the $SPINK5$ gene; its deficiency leads to excessive degradation of desmoglein-1 ($Dsg1$) and abnormal stratum corneum detachment.

Netherton Syndrome

A condition caused by biallelic $SPINK5$ loss-of-function mutations, characterized by severe barrier dysfunction and atopy.

TSLP

Thymic stromal lymphopoietin; known as the "master-switch" of allergic inflammation, it is an $IL-7$-like cytokine that evokes a Th2 response via dendritic cell activation.

IL-31

A Th2 cytokine that links Staphylococcal colonization and pruritus; its receptor is expressed by cutaneous $C$ nerve fibers and dorsal root ganglia.

Nemolizumab

A therapeutic agent that targets the $IL-31$ receptor $A$ subunit to significantly reduce pruritus in moderate–severe atopic dermatitis.

ILC2

Group 2 innate lymphoid cells; an expanded population in atopic dermatitis lesions that promotes Th2 inflammation independent of $T$ cells when stimulated by $TSLP$, $IL-25$, and $IL-33$.

$$Staphylococcus\,aureus$$

The main colonizing organism in over $90\%$ of atopic dermatitis patients, which exacerbates inflammation via superantigenic exotoxins and mucosal barrier impairment.

Roseomonas\,mucosa

A bacterium used in bacteriotherapy to reduce $Staphylococcus\,aureus$ colonization, disease severity, and topical corticosteroid requirements.

Lichenification

Thickened, leathery skin with exaggerated markings caused by chronic scratching or rubbing; a hallmark of the childhood and adolescent/adult stages of atopic dermatitis.

Cheilitis Sicca

Eczema of the lips featuring dry, chapped vermilion lips with peeling and fissuring, commonly occurring in the winter.

Eczema Herpeticum

A rapid, widespread dissemination of herpes simplex virus ($HSV$) over eczematous skin presenting as monomorphic punched-out erosions with hemorrhagic crusting.

EASI

Eczema Area and Severity Index; a validated score used to measure the severity of atopic dermatitis.

POEM

Patient-Oriented Eczema Measure; recommended by the $HOME$ initiative as the core outcome measure in clinical trials and for routine clinical practice.

Spongiosis

The hallmark histologic feature of acute eczema, characterized by intercellular edema in the epidermis which may produce microvesicles or bullae.

Proactive Management

A modern long-term maintenance approach focusing on preventing flares, repairing the skin barrier, and controlling subclinical inflammation rather than only reacting to acute flares.

Syndet

A fragrance-free, non-soap cleanser with neutral or low $pH$ recommended for patients with atopic dermatitis.

Occlusives

A component of moisturizers, such as petrolatum, that functions by preventing water loss from the skin surface.

Topical Calcineurin Inhibitors (TCI)

Non-steroidal anti-inflammatory agents like tacrolimus and pimecrolimus that suppress $T$-cell activation and are particularly useful for the face and intertriginous areas.

Crisaborole

A topical $2\%$ ointment that acts as a $PDE-4$ inhibitor, FDA-approved for mild to moderate atopic dermatitis in patients aged $\ge 3\text{ months}$.

Ruxolitinib Cream

A topical $1.5\%$ $JAK1/2$ inhibitor approved for short-term or non-continuous chronic treatment of mild to moderate atopic dermatitis in patients $\ge 12\text{ years}$.

Dupilumab

A human monoclonal antibody targeting $IL-4R\alpha$ to block $IL-4$ and $IL-13$ signaling; approved for moderate to severe atopic dermatitis in patients $\ge 6\text{ months}$.

Tralokinumab

A biologic agent that targets free $IL-13$ and blocks its interaction with $IL-13R\alpha 1$ and $IL-13R\alpha 2$ receptors.

Upadacitinib

An oral $JAK1$ inhibitor approved for recalcitrant moderate to severe atopic dermatitis in patients $\ge 12\text{ years}$ and weighing $\ge 40\,kg$.

Bleach Bath

An adjunctive therapy using $0.005\%$ sodium hypochlorite to help manage atopic dermatitis, typically prepared with $0.5$ cup of $6\%$ household bleach in a $40$-gallon tub.