Dermatitis: Itchy Red Rashes

Jerry Tan MD FRCP University of W estern Ontario

W

Objectives

• Describe the cutaneous features of dermatitis

• Differentiate acute from chronic dermatitis

• Contrast irritant versus allergic contact dermatitis

• Describe the presentation of atopic dermatitis at

different ages

• Indicate cutaneous findings that are unique for

each type of dermatitis

Dermatitis (syn. eczema)

• Skin inflammation characterized by:

itchy, scaly, patches of ill-defined erythema

• Common reaction pattern of various pathogenic

pathways:

Epidermal barrier disruption

Type IV immune injury

Combinations of the above

Acute dermatitis

erythema and edema

papules, vesicles, and

sometimes bullae

accompanied by

exudation and crusting

Chronic dermatitis

less erythema and

edema

presence of

lichenification, scaling,

and fissuring

Contact Dermatitis

= dermatitis precipitated by an exogenous agent

2 types:

allergic (hypersensitivity) or

irritant (direct noxious effect on skin)

Irritant contact dermatitis

More common than allergic contact dermatitis

Results from chronic exposure to irritants that

progressively disrupt the epidermal barrier

Most common irritants are:

Water

Abrasives

Chemicals, e.g. acids and alkalis

Solvents and detergents

Eg. Irritant contact hand dermatitis

Allergic contact dermatitis

Due to type IV immune response by specific allergen

requires induction and elicitation phase (lag time to

reaction)

Common allergens eliciting contact dermatitis: •

•

•

•

nickel (affects 10% of women and 1% of men),

perfumes,

hair dyes,

rubber latex

• Suspect if dermatitis shows geometric patterns

Nickel Allergy - belt buckle

Nickel Allergy - bracelet

Hair dye allergy

Hair dye allergy

Latex allergy - goggles

Adhesive allergy - bandage

Allergy to leather sandal straps

Management

Primary objective:

Identify offending allergen or irritant

Flare diaries; allergic contact patch

testing

Avoidance of allergen(s) / irritants.

Treatment: Gentle cleansers

Barrier creams

Topical anti-inflammatory medications

Atopic Dermatitis

= chronic pruritic inflammatory

dermatosis

associated with personal or

family history of asthma,

allergic rhinitis, conjunctivitis

or atopic eczema.

Atopy

defines an inherited tendency,

present in 15-25% of the population,

to develop one or more of: asthma, allergic

rhinitis/conjuncitivitis, atopic eczema

Cause of atopic dermatitis:

defective epidermal differentiation (filaggrin mutations) and

resultant impaired barrier function of the skin

Br J Derm 2007, 157: 441

Infantile atopic dermatitis

Infants develop an itchy

vesicular eczema on

cheeks and hands

often with secondary

infection.

scaling

erythema

fissures

Childhood atopic dermatitis

Children develop lesions @ antecubital and popliteal

fossae, neck, wrists, and ankles.

Lichenification, excoriations, and dry skin are common

as well as post-inflammatory hyperpigmentation.

Flexural involvement

xerosis

excoriations

Erythematous patches, fissures

hyperpigmentation

Lichenification Accentuation of normal skin markings

Adult atopic dermatitis

In adults

most common manifestation: hand dermatitis.

chronic severe form of generalized and lichenified

atopic eczema.

Hand dermatitis

Widespread chronic atopic dermatitis

Complications of atopic dermatitis

Infection:

Bacterial infection: impetigo

Viral infection

eczema herpeticum

(HSV)

widespread mollusca

Cataracts Growth retardation

Impetiginised dermatitis

Golden yellow crust

Impetiginised dermatitis

Fragile bullae with crust and erosions = bullous impetigo

Eczema Herpeticum

Extensive facial erosions More tender than typical eczema

Mollusca Contagiosa

Dome-shaped 1-2mm firm papules

Management

Education

Avoidance of irritants

sweat, wool, pet dander

Mild cleansers, frequent moisturisation

Prescribe the least potent topical anti-inflammatory

(steroid, TIMs) that is effective.

Antibiotics (topical or oral) for infected eczema.

+/- oral antihistamines for pruritus

Topical Steroid Classification

Potency Products

Hydrocortisone acetate 1%

Comments

Facial and intertriginous Low

Moderate

Strong

Ultra

Desonide

Betamethasone valerate Triamcinolone acetonide Mometasone

Amcinonide Betamethasone dipropionate

Clobetasol, Halobetasol

regions Elidel* equivalent

Protopic* 0.1% equivalent

Limit use to max 1 wk/ mth Reassess frequently

*Non-steroidal antiinflammatory medications

Seborrheic dermatitis

chronic, scaly inflammatory eruption usually

affecting scalp and face

Can also affect chest, and flexures (axillae, groin, and

infra-mammary areas)

due to overgrowth of the commensal yeast

Pityrosporum ovale.

Seborrheic dermatitis

•Persistent

erythematous patches

with greasy scales

•Characteristic

distribution: sides of

nose, glabella,

perioral region, scalp,

eyebrows, ears;

chest.

Seborrheic dermatitis

Truncal seborrheic dermatitis

Management

Scalp:

medicated shampoo (e.g. containing coal tar,

selenium sulphide or ketoconazole)

Face, trunk, flexures:

imidazole or antimicrobial, often combined with low

potency topical steroid

eg HC 1% in Canesten Cream bid

Nummular Eczema

Distinctive eczema with itchy coin-shaped

macules/patches

typically affects limbs of middle-aged or elderly

Management:

emollient,

topical steroid

Nummular Eczema

Venous (Stasis) Eczema

affects sites of stasis edema (lower legs)

most patients are middle-aged or elderly

Complications: ulcers, infections

Management: • Treatment of edema

• Support stockings, leg elevation, diuretics

• Skin treatment: emollient +/- steroid ointment

Stasis eczema

Stasis eczema

Xerotic dermatitis

Diffuse background skin dryness with associated

dermatitis

typically affects limbs of the elderly.

Aggravated by:

harsh cleansers, dry winter conditions, hypothyroidism, use of

diuretics

Treat with emollients 1st;

+/- mild steroid ointments

Xerotic dermatitis

What unique features are associated with different types

of dermatitis?

Distinctive morphological features of different forms of dermatitis

type Features of dermatitis Other skin findings

atopic Symmetry, changes with age xerosis

seborrheic Greasy scale, face and scalp affected oiliness

nummular

stasis

xerotic

Coin-shaped or discoid macules and patches

Affects lower legs, ankles

Mild, widespread; typically fall & winter

xerosis

Edema, hyperpigmentation

xerosis

allergic contact sites of contact,

may have geometric patterns

irritant contact typically affects hands, face Xerosis, fissuring

Summary

• Describe the cutaneous features of dermatitis

• Differentiate acute from chronic dermatitis

• Contrast irritant versus allergic contact dermatitis

• Describe the presentation of atopic dermatitis at

different ages

• Indicate cutaneous findings that are unique for

each type of dermatitis

Acknowledgements References:

Shear, Knowles and Shapiro Cutaneous Drug Reactions, Web MD Scientific American, Feb 2001.

Lebwohl, M: Cutaneous Manifestations of Systemic Diseases, WebMD Scientific American Medicine, June 2003 update.

Gawkrodger DJ. Dermatology an illustrated color text. Churchill Livingstone 2001

Illustrations: Dermatology Image Atlas: www.dermatlas.org

www.dermis.net www.derm101.com