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Patch Testing
T-cell mediated diseases: Principles and Practice
Ana M Giménez Arnau
Department of Dermatology and Venereology.
Hospital del Mar. Universitat Autònoma. Barcelona. Spain
a.g.a Erlanguen 2013
Contact Dermatitis
How important is in your daily practice
• Contact Dermatitis is an inflammatory skin reaction to direct
contact with noxious agents in the environment
• This entity was recognized as disease in ancient times. Early
recorded reports include Pliny the Younger who, in the first
century A.D., noticed individuals with severe itching when
cutting pine trees
• The history of contact dermatitis in the twentieth century is
indistinguishable from the history of patch testing, which is
considered the main tool for discover the etiology being a
chemical or a protein involved
a.g.a Erlanguen 2013
Contact Dermatitis. Fifth Edition .
Eds Jeanne Duus Johansen, Peter J Frosch , Jean-Pierre Lepoittevin.
Springer-Verlag Berlin Heidelberg 2011.
Dermatitis and Eczema
Are these synonyms or do they mean distinct entities?
• Dermatitis means inflammation of the skin
• Eczema, from Greek, term ekzein, “to boil over”,
relates to the spongiotic vesiculation of the
epidermis characteristic of some stages
There are not a disease in itself,
but comprises a group of skin disorders exhibiting a
common pattern of histological and clinical findings which
vary depending on the stage of the disease
a.g.a Erlanguen 2013
Contact Dermatitis. Fifth Edition .
Eds Jeanne Duus Johansen, Peter J Frosch , Jean-Pierre Lepoittevin.
Springer-Verlag Berlin Heidelberg 2011.
Eczema
Greek, term ekzein, “to boil over” - vesicle
Acute
Hospital del Mar.
a.g.a Erlanguen 2013
Chronic
• Itchy cutaneous
inflammation
• erythema
• vesiculation,
• exudation,
• crust and
• lichenification.
Eczema
Greek, term ekzein, - spongiosis and exocytosis
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a.g.a Erlanguen 2013
acanthosis
espongiosis
exocytosis
dermal
inflammatory
infiltrate
Eczema
vesiculation / espongiosis and exocytosis - types
• contact
Hospital del Mar.
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a.g.a Erlanguen 2013
• irritant
• allergic
• photo allergy
• photo toxicity
atopic
nummular
drug induced
dishidrotic
microbial
Contact Dermatitis
Epidemiology
• There is difficult to establish the prevalence or incidence of contact
dermatitis in general population from clinical epidemiology
• Prevalence of hand eczema, contact sensitivity and contact dermatitis in
general population from cross-sectional studies,
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lifetime prevalence of hand eczema of 9%
1-year period prevalence of 7.3%
point prevalence of 3.2%
The point prevalence of contact allergy was 15%
Most common contact allergens nickel (8.6%) & fragrance mix (1.8%)
a.g.a Erlanguen 2013
Mortz cG, Lauritsen JM, Bindslev-Jensen C, Andersen KE. Contact allergy and allergic contact dermatitis in
adolescents: prevalence measures and associations. The Odense adolescents Cohort Study on Atopic
Diseases and Dermatitis (TOACS). Acta Derm Venereol 2002;82: 352-358
Contact Allergens
Clinical patterns
• eczema
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erosions,
ulcerations,
urticaria,
erythema multiforme,
purpura,
lichenoid eruptions,
exanthemas,
erythroderma,
allergic contact granuloma,
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lymphocytoma,
sarcoidal reactions,
toxic epidermal necrolysis,
pigmented contact
dermatitis,
contact leukoderma,
nodular lesions
photosensitive reactions
generalized symptoms
contact urticaria may
become anaphylaxis.
Diagnosis
Allergic Contact Dermatitis
 Assess type of eczema and suspected trigger factor
 Assess active principle and excipient
 Repeat Open Application Test, ROAT
Immediate
Open patch test
Occluded patch test
Photo patch test
Scratch test
Photo Prick test
Prick test
Intradermal test
Delayed
Occluded patch test
Semioccluded patch test
Scratch test
Intradermal test
Subcutaneous test
Diagnosis
Allergic Contact Dermatitis - Patch Test
• First introduced by Jadassohn in 1896
• Is the gold standard method for the detection of the
causative contact allergens
• The positive patch test reproduces an experimental
contact dermatitis on a limited area of the skin
• A good patch test indicates contact sensitization of past or
present relevance
Allergic Contact Dermatitis
Diagnosis – reading 2, 4 and 7 days
• Negative (-)
• Doubtfull (+/-):
• Mild erythema
• Positive mild (+):
• erythema, infiltration, papule
• Positive (++):
• erythema, infiltration, papule, vesicles
• High Positive reaction (+++):
• erythema, infiltration, papule, vesicles, bullae
• No desirable : Necrosis
Hospital del Mar.
Allergic Contact Dermatitis
Patch test contraindications
Active or widespread dermatitis
Excessive sun exposure
Systemic steroids (> 20 mg, > 1 month)
Topical steroids at the site of patch test
Systemic immunosuppressant
Pregnancy
Hospital del Mar.
Dermographism
Allergic Contact Dermatitis
Patch Test Complications
Ungry Back
Likely to develop in patients with a longer duration of the
primary dermatitis
Causes, strongly positive reaction or skin hyper-reactivity
Later sequential testing with each substance alone is
recommended
Allergic Contact Dermatitis
Patch test complications
• Irritant reactions,
• Test only normal appearing skin
• Do not prepare skin by cleansing with soap or solvents
• Avoid testing with non-standardized materials
• Don’t patch test if widespread dermatitis or status eczematicus
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Flare of ectopic dermatitis
Koebner phenomenon
Persistent reaction , > 1 month e.g. gold
Alteration of pigmentation, avoid hydroquinone
Anaphylactoid reactions, e.g. ammonium persulfate
Edge efect, habitually dissapear
Pustular reaction
Pressure effect
Bacterial and viral infection
Necrosis, scars and keloids
• Pseudolymphoma (gold and metals)
Allergic Contact Dermatitis
Patch Test Complications
Active sensitization
• Positive patch test 7 or more days later with no early positivity
• Interactions of residues of allergen with newly sensitized tissues
• Detection:
• Positive patch test 14 days after application (flare-up)
• 2 – 4 days after later repetition of patch test
• Most common cause:
• Use of too high concentration of the test substance
• Active sensitization is rare with standard allergens
• Causative allergens: e.g. Paraphenylenediamine (PPD)
Allergic Contact Dermatitis
Patch Test indications
1. Patient with suspected allergic contact dermatitis
2. To confirm the offending antigen even if obvious
3. Atopic dermatitis exacerbated by ACD
4. Preexisting dermatitis superimposed by ACD (e.g.: stasis dermatitis)
5. Occupational contact dermatitis
6. Chronic hand dermatitis
7. Photodermatitis (sunscreens, topical NSAIDs)
8. Contact Urticaria (latex, metals, epoxy resins)
9. Protein contact dermatitis (amylase, rat hair, crab meat)
10. Adverse drug eruption (AGEP, maculopapular, FDE, erythroderma)
11. To identify potential health hazards of newly introduced potential allergens
for the medical community and industrial hygienist
• Patch test all the patients with hand eczema
longest than three months or at least two
acute forms per year, with the objective to
identify the role of contact allergens in its
pathogenesis
• Clinical relevance of contact allergens is
independent from the clinical pattern and its
severity
Allergic Contact Dermatitis
Semiocclusive Patch test
. Direct
application on the skin, with a cotton Q-tip, of an amount
(1 to 2 µl) of a liquid on a skin surface of about 1 cm2
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After complete evaporation of the liquid (the excess can be
removed with a paper filter or another Q-tip)
. The completely dry test site is then covered with acrylic tape
. Also diluted products (e.g. 1-2 % aqueous) tested this way
. Reading of the skin test is performed as regular patch testing
Dooms-Goossens A (1995) Patch testing without a kit: In Guyin JD (ed) Practical Contact Dermatitis . McGraw-Hill , New York , pp 63-74
Allergic Contact Dermatitis
How important is in our daily life ?
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High prevalence
Model pathogenesis needs further inside
Broad spectrum of trigger factors
Improve diagnostic tools
Quality of life impairment
Occupational relevance
Multidisciplinary approach
Work in Networks
Human health hazards
New therapy
Preventive measures
Regulatory affairs