Dermatitis
M. Nasimi, M.D.
Tehran University of Medical
Sciences
Introduction
Eczema is an inflammatory skin reaction
characterized histologically by spongiosis with
varying degrees of acanthosis, and a
superficial perivascular lymphohistiocytic
infiltrate.
The clinical features of eczema Include :
itching,
redness,
Plaque, papules , vesicles
scaling
Acute Eczema
Erythema,
edema
vesicle or bullae,
Oozing or crusting;
Subacute Eczema
Erythematous scaly plaque with indistinct margin
Moderate to severe pruritus
Chronic eczema
Scaly, erythematous plaque
Marked lichenification
Prolonged pruritus
fissuring
Such staging is only for convenience of
description, as the stages often overlap within
a given patient.
Classification of the principal
forms of eczema
Exogenous eczemas
Irritant contact dermatitis
Allergic contact dermatitis
Photoallergic contact dermatitis
Eczematous polymorphic light eruption
Infective dermatitis*
Dermatophytide*
Post-traumatic eczema*
Endogenous eczemas
Atopic dermatitis
Seborrhoeic dermatitis*
Asteatotic eczema*
Discoid eczema*
Exudative discoid and lichenoid dermatitis*
Chronic superficial scaly dermatitis*
Pityriasis alba*
Hand eczema*
Gravitational eczema*
Juvenile plantar dermatosis*
Metabolic eczema or eczema associated with systemic disease*
Eczematous drug eruptions*
Irritant contact dermatitis
ICD is a localized inflammatory skin response
to a wide range of chemical or physical agents.
ICD results from direct cytotoxic effect of
irritants; unlike allergic contact dermatitis
(ACD) it is not immune mediated.
EPIDEMIOLOGY
ICD is the most common type of contact
dermatitis.
The risk of occupational ICD is highest among
those with "wet work" exposures such as food
handlers, healthcare workers, mechanical
industry workers, cleaners, and housekeepers .
PATHOGENESIS
Multiple mechanisms are involved in the
development of ICD, including :
Disruption of the epidermal barrier
Damage of cell membranes
Cytotoxic effect on keratinocytes
Cytokine release from keratinocytes
Activation of innate immunity
PREDISPOSING FACTORS
Host-related factors
Age — The skin reactivity to irritants is highest
in infants and tends to decrease with age.
Sex — The prevalence of ICD in general and of
hand dermatitis in particular is greater in
women than in men. However, the higher risk
in women is probably due to “wet work” rather
than to genuine sex differences in
susceptibility.
Body site — The response to irritants varies
from site to site on the body, reflecting
differences in the thickness of the stratum
corneum . The face, dorsum of the hands, and
finger webs are more prone to irritation from
chemical substances than the palms, soles, or
back.
Atopy
Genetic factors
The most important predisposing factor for ICD
is a history of atopic dermatitis.
HISTOPATHOLOGY
The histologic features of irritant contact
dermatitis (ICD) vary according to the stage
and severity of skin lesions:
Acute ICD is characterized by spongiosis,
intraepidermal vesicles or bullae, and necrosis of
keratinocytes. A perivascular mononuclear cell
infiltrate may be seen.
Chronic ICD is characterized by hyperkeratosis,
parakeratosis, hypergranulosis, and acanthosis.
None of the histopathologic
features of ICD can
differentiate it from ACD.
COMMON IRRITANTS
Common chemical irritants include
water and wet work, detergents and
surfactants, solvents, oxidizing agents,
acids, and alkalis.
Physical irritants include metal tools,
wood, fiberglass, plant parts, paper, and
dust or soil.
CLINICAL
MANIFESTATIONS
The clinical manifestations of ICD range from:
mild skin dryness and erythema to
acute or chronic eczematous dermatitis and
even skin necrosis (chemical burn).
Acute ICD
Acute ICD often results from a single exposure
to an irritant.
Clinical features include erythema, edema,
vesicles, bullae, and oozing.
The reaction is generally limited to the site of
contact and is associated with a sensation of
burning, stinging, or pain.
Chronic ICD
Chronic ICD result from repeated exposures to
mild irritants.
Clinically, chronic ICD is characterized by
erythema, scaling, lichenification,
hyperkeratosis, and fissuring.
Sites commonly affected are the
dorsum of the hands,
fingertips, and
finger webs.
Secondary infection (especially
with S.aureus) are common in all
forms of dermatitis:
Pustule
impetiginization
DIAGNOSIS
The diagnosis of ICD is in most cases based
upon the clinical finding of a localized
dermatitis in a patient with a history of
exposure to irritants.
Patch testing is performed in refractory cases
to exclude allergic contact dermatitis.
In some cases, skin biopsy for histologic
examination is necessary to exclude other skin
Important aspects of the history in a patient with
suspected ICD include:
Daily activities, including occupation and hobbies
Types of substance or machinery used at the workplace
Workplace environment (temperature, humidity, dusts)
Use of protective gloves
Wet work (including use of occlusive gloves)
Hand washing habits
Use of cleansers and skin protecting creams
Accidental exposure
Previous atopic dermatitis, or other inflammatory skin
disease
DIFFERENTIAL
DIAGNOSIS
Allergic contact dermatitis
Atopic dermatitis
Psoriasis
Fungal infection
MANAGEMENT
Identification and avoidance of the
offending irritants
Treatment of skin inflammation
Restoration of the epidermal barrier
function
Avoidance:
Avoidance of irritants and are critical in the
management of ICD. For hand dermatitis,
general measures include:
Minimizing contact with detergents or other cleaning agents,
Using plastic gloves with cotton lining if wet work cannot be
avoided
Wearing gloves in cold weather
Using small amounts of mild skin cleansers for hand
washing
Rinsing and drying hands thoroughly and gently after
washing
Using moisturizers multiple times per day
Active treatment
Active treatment of ICD is aimed at reducing
the signs and symptoms of inflammation.
Topical corticosteroids and emollients are
used.
Topical corticosteroids
For severe acute ICD or chronic ICD with skin thickening
(lichenification) not involving the face or flexural areas:
a super high potency topical corticosteroid (eg,
clobetasol propionate). Topical corticosteroids are
applied once or twice daily for two to four weeks.
For milder forms of ICD not involving the face or flexural
areas: a high potency corticosteroids (eg, fluocinonide
or betamethasone dipropionate).
For acute or chronic ICD involving the face or flexural
areas, we suggest medium or low-potency topical
corticosteroids (eg, triamcinolone acetonide or
hydrocortisone acetate). Topical corticosteroids are
applied once or twice daily for one to two weeks.
Emollients
Emollients or moisturizers are beneficial in all
patients with ICD.
Emollients are used to decrease irritation and
improve or restore the skin barrier function in
ICD.
Emollients should be liberally applied multiple
times per day, particularly after hand washing,
and after work.
Second-line therapy
Topical calcineurin inhibitors: tacrolimus,
pimecrolimus
Systemic corticosteroids
Systemic immunosuppressive agents:
azathioprine, cyclosporine, mycophenolate
mofetil
Phototherapy
Prevention
Gloves
Barrier creams: Barrier creams are
designed to reduce the penetration of
hazardous materials into the skin.
Allergic contact dermatitis
ACD is a common inflammatory skin disease
presenting with pruritic, eczematous lesions.
ACD results from a T cell-mediated, delayed
type hypersensitivity reaction (type IV).
Pathogenesis
antigen engulfed by the Langerhans cell (epidermal
APCs)
processing of antigen
presented to T-lymphocytes in regional lymph nodes
sensitized T-lymphocytes produced in the nodes
released back into the circulation
preferentially arrive at sites where antigen is present
Sensitization: 10 to 14 days.
Reexposure: antigen presented to sensitized
lymphocytes → release cytokines → clinical picture of
inflammation
reexposure : 12 to 48 hours
Risk factors
Occupation – Workers at highest risk of ACD
include health professionals, chemical industry
workers, beauticians and hairdressers,
machinists, and construction workers.
Age – ACD was once considered a disorder of
the adult population.
Children were thought to be spared because of a
low exposure to potential allergens and an
immature immune system.
The incidence of ACD increases with age.
Common allergens
PLANTS: Poison ivy
METALS: nickel, cobalt, chromium,
gold
PRESERVATIVES: Formaldehyde,
Quaternium-15, Parabens, Propylen
glycol
FRAGRANCES
TOPICAL MEDICATIONS:
Anesthetics, Antibiotics (neomycin,
bacitracin, polymyxin B),
Corticosteroids
Allergens:The top 10
allergens identified by North American
Contact Dermatitis Group
1-Nickel
2-Neomycin
3-Balsam of Peru
4-Fragrance mix
5- Thimerosal
6- Sodium gold thiosulfate
7- Quaternium-15
8- Formaldehyde
9- Bacitracin,
10-Cobalt
CLINICAL FEATURES
Acute ACD lesions consist of erythematous,
edematous plaques. Vesiculation and bullae
may be seen in severe cases.
Edema may be prominent in areas in which the
skin is thin, such as the eyelids, lips and
genitalia.
Repeated or continued exposure to allergens
results in chronic disease. Lichenification and
fissuring may develop later.
The involvement of hands, face, or eyelids, which most
commonly come in contact with the environment, occurs
most frequently in ACD.
Allergens applied to the scalp, including hair dyes and
shampoos, may elicit dermatitis in adjacent areas, such as
the neck, retroauricular folds or eyelids.
Facial lesions may result from direct contact with cosmetic
products or from involuntary transfer of allergens to the
face (eg, eyelid ACD from nail polish).
A diffuse or patchy dermatitis of the trunk, often with
accentuation in the axillary folds, may be caused by cloth
dyes or textiles.
Contact dermatitis due to
nickel
Acute bullous allergic
contact dermatitis due to
poison ivy
Allergic contact dermatitis
to leather shoes
Diagnosis
The diagnosis of ACD is based upon a
combination of:
Clinical features (morphology, location, and
symptoms) of the eruption
History of exposure to a putative allergen
during work, hobbies, or home activities
Patch testing results
Lack of recurrence after empirical treatment of
the dermatitis and avoidance of the suspected
allergen
A history of long term exposure to an allergen
does not rule out contact allergy, since
multiple exposures may be necessary for
sensitization and dermatitis to occur.
In addition, an individual’s susceptibility to
ACD may change over time because of aging
or comorbidities .
Management
The optimal management of ACD requires a
multipronged approach:
Identification and avoidance of the offending
allergen
Treatment of skin inflammation
Restoration of the skin barrier
Patch test
Patch testing is an essential
investigation in patients with
persistent eczematous eruptions
when contact allergy is suspected.
Procedure of Patch Testing
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