eMedicine Specialties > Emergency Medicine > Dermatology

Dermatitis, Contact: Differential Diagnoses & Workup

Author: Bradley D Shy, MD, Staff Physician, Department of Emergency Medicine, New York University School of Medicine/Bellevue Hospital Center
Coauthor(s): David Todd Schwartz, MD, Associate Professor of Emergency Medicine, New York University School of Medicine; Attending Physician, Department of Emergency Medicine, Bellevue Hospital Center and New York University Medical Center
Contributor Information and Disclosures

Updated: Sep 22, 2009

Differential Diagnoses

Bites, Insects
Herpes Zoster
Cellulitis
Herpetic Whitlow
Dermatitis, Atopic
Impetigo
Dermatitis, Exfoliative
Psoriasis
Erysipelas
Scabies
Erythema Multiforme
Vulvovaginitis
Herpes Simplex

Other Problems to Be Considered

Properly differentiating between irritant contact dermatitis (ICD) and allergic contact dermatitis (ACD) will rarely change initial ED management, but it may aid in the identification of the offending agent and prevent reinjury. ICD can occur secondary to the first lifetime exposure to an agent, whereas ACD requires an initial sensitization to an offending antigen before an inflammatory reaction can occur. ICD is dose-dependent and has a threshold of exposure below which no reaction will occur.1  Following prior sensitization, ACD can occur after any amount of contact with an antigen. Additionally, ICD only occurs in the discreet areas of direct contact with the offending chemical, whereas ACD can involve the surrounding skin and other tissues. Pruritus is more common in ACD, whereas pain and burning are more typical of ICD.7
 
Before making the diagnosis of contact dermatitis, cellulitis should be excluded. On physical examination, both contact dermatitis and cellulitis can present with poorly marginated areas of erythema and occasionally edema. Cellulitis can be best differentiated by taking a focused patient history. Furthermore, cellulitis can cause pain, in contrast to the pruritic quality of ACD. Finally, cellulitis can be associated with fever, malaise, local lymphadenopathy, and leukocytosis; none of these findings are consistent with contact dermatitis. If skin blistering has occurred, herpes zoster as well as herpes simplex and impetigo should also be considered.
 
Atopic dermatitis (often referred to as eczema) is a chronic inflammatory skin condition most common in children. It can have a clinical presentation similar to that of ACD and ICD. Atopic dermatitis can be perpetuated by soaps, detergents, and other agents that are also implicated in contact dermatitis. However, atopic dermatitis usually presents with a flexural distribution of the limbs and neck, unlike the local distribution of ACD and ICD. See Dermatitis, Atopic for further discussion.

Nummular eczema
Lichen simplex chronicus
Stasis dermatitis
Xerosis

Workup

Laboratory Studies

  • Laboratory examination of allergic contact dermatitis (ACD) focuses on patch testing. In this examination, a dermatologist or an allergist applies multiple potential allergens into the skin of the patient. The presence of erythema, papules, or vesicles can indicate a positive test. Patch testing is most accurate several weeks after the resolution of the dermatitis, and thus has no role in the ED.

Imaging Studies

  • No ED imaging studies are of value in diagnosing contact dermatitis.

Other Tests

  • Patch testing may be beneficial to identify the contact allergen and is usually performed in an outpatient setting.

Procedures

  • Pathologic findings obtained from biopsy specimens include intercellular edema and bullae.

More on Dermatitis, Contact

Overview: Dermatitis, Contact
Differential Diagnoses & Workup: Dermatitis, Contact
Treatment & Medication: Dermatitis, Contact
Follow-up: Dermatitis, Contact
Multimedia: Dermatitis, Contact
References
Further Reading
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References

  1. Wolff K, Johnson RA, Suurmond D. Contact dermatitis. In: Fitzpatrick's Color Atlas & Synopsis of Clinical Dermatology. 5th ed. New York: McGraw-Hill; 2005.

  2. Engkilde K, Menne T, Johansen JD. Inverse relationship between allergic contact dermatitis and type 1 diabetes mellitus: a retrospective clinic-based study. Diabetologia. Apr 2006;49(4):644-7. [Medline].

  3. Spoo J, Elsner P. Cement burns: a review 1960-2000. Contact Dermatitis. Aug 2001;45(2):68-71. [Medline].

  4. Agin PP, Ruble K, Hermansky SJ, McCarthy TJ. Rates of allergic sensitization and irritation to oxybenzone-containing sunscreen products: a quantitative meta-analysis of 64 exaggerated use studies. Photodermatol Photoimmunol Photomed. Aug 2008;24(4):211-7. [Medline].

  5. [Guideline] SGNA Practice Committee. Guideline for preventing sensitivity and allergic reactions to natural rubber latex in the workplace. Gastroenterol Nurs. May-Jun 2008;31(3):239-46. [Medline].

  6. Modi GM, Doherty CB, Katta R, Orengo IF. Irritant contact dermatitis from plants. Dermatitis. Mar-Apr 2009;20(2):63-78. [Medline].

  7. Edwards L. Acute allergic contact dermatitis. In: Dermatology in Emergency Care. New York: Churchill Livingstone; 1997:53-55.

  8. [Guideline] American Academy of Allergy, Asthma and Immunology, American College of Allergy, Asthma and Immunology. Contact dermatitis: a practice parameter. Ann Allergy Asthma Immunol. Sep 2006;97(3 Suppl 2):S1-38. [Medline]. [Full Text].

  9. Ong PY, Boguniewicz M. Atopic dermatitis and contact dermatitis. Clin Pediatr Emerg Med. 2007;8(4):81-86.

  10. Arndt KA. Archives of Dermatology. Second century. Arch Dermatol. Jan 1984;120(1):42-3. [Medline].

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Further Reading

See Contact Dermatitis for an excellent review of contact dermatitis with a focus on the pediatric population. 9

An illustrated summary of contact dermatitis with special attention to the presentation in the ED can be found in the chapter on this disease in Dermatology in Emergency Care by Libby Edwards. 7

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Keywords

allergic contact dermatitis, ACD, cell-mediated type IV delayed hypersensitivity reaction, contact allergen, contact urticaria, ICD, irritant contact dermatitis, diaper dermatitis, photodermatitis, photoallergic reactions, phototoxic reactions, photodermatitis, poison ivy, poison oak, poison sumac, rhus dermatitis, Toxicodendron, type I IgE-mediated reaction

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Contributor Information and Disclosures

Author

Bradley D Shy, MD, Staff Physician, Department of Emergency Medicine, New York University School of Medicine/Bellevue Hospital Center
Disclosure: Nothing to disclose.

Coauthor(s)

David Todd Schwartz, MD, Associate Professor of Emergency Medicine, New York University School of Medicine; Attending Physician, Department of Emergency Medicine, Bellevue Hospital Center and New York University Medical Center
David Todd Schwartz, MD is a member of the following medical societies: American Academy of Emergency Medicine and American College of Emergency Physicians
Disclosure: Nothing to disclose.

Medical Editor

Mark Louden, MD, FACEP, Assistant Medical Director, Emergency Department, Duke Raleigh Hospital
Mark Louden, MD, FACEP is a member of the following medical societies: American Academy of Emergency Medicine and American College of Emergency Physicians
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: eMedicine Salary Employment

Managing Editor

Mark W Fourre, MD, Program Director, Department of Emergency Medicine, Maine Medical Center; Associate Clinical Professor, Department of Surgery, University of Vermont School of Medicine
Disclosure: Nothing to disclose.

CME Editor

John D Halamka, MD, MS, Associate Professor of Medicine, Harvard Medical School, Beth Israel Deaconess Medical Center; Chief Information Officer, CareGroup Healthcare System and Harvard Medical School; Attending Physician, Division of Emergency Medicine, Beth Israel Deaconess Medical Center
John D Halamka, MD, MS is a member of the following medical societies: American College of Emergency Physicians, American Medical Informatics Association, Phi Beta Kappa, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

Chief Editor

Barry E Brenner, MD, PhD, FACEP, Professor of Emergency Medicine, Professor of Internal Medicine, Program Director, Emergency Medicine, University Hospitals, Case Medical Center
Barry E Brenner, MD, PhD, FACEP is a member of the following medical societies: Alpha Omega Alpha, American Academy of Emergency Medicine, American College of Chest Physicians, American College of Emergency Physicians, American College of Physicians, American Heart Association, American Thoracic Society, Arkansas Medical Society, New York Academy of Medicine, New York Academy of Sciences, and Society for Academic Emergency Medicine
Disclosure: Nothing to disclose.

 
 
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