Patch Testing

Aka: Patch Testing, Patch Test

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II. Indications

  1. Allergic Contact Dermatitis (Type 4 Hypersensitivity)

III. Mechanism

  1. Contact Dermatitis is a delayed T cell-mediated response (Type 4 delayed Hypersensitivity)
  2. Most common contact allergans
    1. Rhus Dermatitis (e.g. Poison Ivy)
    2. Nickel Allergy
    3. Cosmetic allergy
    4. Rubber product allergy (Latex Allergy)

IV. Efficacy: Evaluating Allergic Contact Dermatitis

  1. Test Sensitivity: 70%
  2. Test Specificity: 70%

V. Technique

  1. Place drop of each diluted agent in Patch Test chamber
  2. Apply patch to non-irritated, clean skin of back
  3. Outline each patch outline with pen
  4. Label agent locations on skin and in medical record
  5. Remove patch in 48 hours
  6. Measure skin reaction (see below)

VI. Approach: Interpretation of skin test

  1. Erythema: 1+ (Mild)
    1. Accuracy 20%
  2. Edema or Vesicles involve <50% of patch area: 2+
  3. Edema or Vesicles involve >50% of patch area: 3+
    1. Accuracy 90%

VII. Causes: False Positive (consider if multiple positives)

  1. Hyperirritability of skin
  2. Contaminant irritant or allergen on tested skin
  3. Reaction to tape holding patch in place
  4. Irritant Contact Dermatitis
    1. Reaction resolves more quickly than in allergy
    2. Burning Sensation contrasted with itching in allergy
    3. Sharply demarcated reaction

VIII. References

  1. Chang (2018) Am Fam Physician 98(1): 34-9 [PubMed]
  2. Mydlarski in Middleton (1998) Allergy, Mosby, p. 1141-2 [PubMed]
  3. Riedl (2003) Am Fam Physician 68:1781-90 [PubMed]

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Related Studies

Ontology: Patch Tests (C0030646)

Definition (MSH) Skin tests in which the sensitizer is applied to a patch of cotton cloth or gauze held in place for approximately 48-72 hours. It is used for the elicitation of a contact hypersensitivity reaction.
Concepts Diagnostic Procedure (T060)
MSH D010328
SnomedCT 268402005, 142167009, 164995003, 41778007
CPT 95044
English Patch Test, Test, Patch, Tests, Patch, Patch skin test, patch testing, patch testing (lab test), Patch or application test(s) (specify number of tests), patch test, test patch, patch skin testing, PATCH/APPLICATION TEST SPECIFY NUMBER TESTS, Skin patch test, Patch test, PT - Patch test, Patch test (procedure), Patch test, NOS, ALLERGY PATCH TESTS, Allergy patch tests, Patch Tests, Test;skin patch, skin patch test
Dutch huidpatch test, Test, epicutane, Tests, epicutane
French Patch-test cutané, Patch-tests, Tests épicutanés, Épidermotests
German Hautpatchtest, Pflasterproben
Italian Test della cute con cerotto, Patch test
Portuguese Prova de selo da pele, Testes do Emplastro
Spanish Prueba de parche cutáneo, Tests del Parche, prueba de sensibilidad cutánea, prueba del parche (procedimiento), prueba del parche, Pruebas del Parche
Japanese 皮膚パッチテスト, ﾋﾌﾊﾟｯﾁﾃｽﾄ
Swedish Lapptester
Czech náplasťové testy, Náplasťový test
Finnish Lappukokeet
Russian KOZHNYE TESTY NA GIPERSENSIBILIZATSIIU, GIPERSENSIBILIZATSIIA, KOZHNYE TESTY, KOZHNYE TESTY KONTAKTNYE, ГИПЕРСЕНСИБИЛИЗАЦИЯ, КОЖНЫЕ ТЕСТЫ, КОЖНЫЕ ТЕСТЫ КОНТАКТНЫЕ, КОЖНЫЕ ТЕСТЫ НА ГИПЕРСЕНСИБИЛИЗАЦИЮ
Polish Próba plasterkowa, Próba płatkowa, Testy płatkowe
Hungarian Bőr tapasz vizsgálat
Norwegian Lappeprøver, Eksemprøver
Derived from the NIH UMLS (Unified Medical Language System)

Related Topics in Pathology and Laboratory Medicine

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