Diagnosing and treating contact dermatitis

Contact dermatitis is an inflammatory skin condition caused by exposure to an external irritant or allergen. The result of the exposure is either an irritant contact dermatitis (ICD) or allergic contact dermatitis (ACD), although they can coexist.[1] These exposures can occur in occupational and non-occupational settings. ICD accounts for approximately 80% of all occupational skin diseases in BC, which is consistent with incidents reported in international occupational disease literature.[1,2,4] 

ICD is a nonimmunologic response to chemicals or physical agents that cause direct damage to the skin faster than the skin can self-repair. Common irritants include soaps, cleaners, alcohols, solvents, cutting oils, degreasers, friction, and wet work.[1-4] ICD can present both acutely from a caustic exposure, and over time from multiple weak irritant exposures, such as frequent and prolonged exposure to wet work.

ACD is a type IV delayed hypersensitivity reaction to an external allergen that occurs only in individuals who have previously been sensitized. Re-exposure elicits an immunologic response that causes skin inflammation typically within 48 hours. Common allergens include metals, particularly nickel; chromates; preservatives; glues; cosmetics; rubber accelerators; acrylics; plants; and topical medications, such as neomycin and corticosteroids.[4]

Symptom inquiry includes the pattern for the onset of skin symptoms, the areas of skin involved, potential triggers (non-occupational, recreational, or occupational), the patient’s daily skin routine, and all topical products used. Work history should include hand-washing requirements; glove use, including type of gloves; and improvement of symptoms when away from work. A medical and family history inquiry should include asthma, eczema or other skin conditions, and atopy.[1,3-5]

While medical history, onset, location, pattern, and temporal associations provide clues for ascertaining the type of dermatitis, clinically distinguishing between ICD, ACD, and other types of dermatitis can be difficult. For both ICD and ACD, a clinical exam during the acute phase may show erythema, edema, papules, vesicles, and bullae. An exam during the chronic phase may show dryness, scaling, lichenification, hyperkeratosis, and fissuring. Pain and burning may be more common in ICD, contrasting the usual itch of ACD.[6] 

Suspected cases of ACD should be referred for patch testing, which is the gold standard for diagnosing allergic contact dermatitis using the standard contact allergen series, plus suspected allergens, where necessary.

Differential diagnoses for contact dermatitis include atopic dermatitis, dyshidrotic eczema, contact urticaria, psoriasis, fungal infection, seborrheic dermatitis, periocular dermatitis, photodermatitis, and systemic conditions such as systemic lupus erythematosus, dermatomyositis, dermatitis herpetiformis, and porphyria cutanea tarda.[3,4]

Key to managing contact dermatitis is early identification and avoidance of underlying causes, such as triggering irritants or allergens at home, in recreational activities/hobbies, and in the workplace. While appropriate gloves can assist with avoidance, gloves can sometimes worsen ICD and ACD in individuals who are sensitized to rubber accelerators.[2,4,5] Using cotton glove liners may mitigate the effects attributed to long-term occlusive glove use associated with some cases of ICD.[2,5]

Recommended first-line treatments for contact dermatitis include emollients to improve skin barrier function, and topical corticosteroids, with ointment preferred over cream.[1-4] In more severe cases, topical immune modulators may be required, along with a referral to a specialist for consideration of phototherapy, oral retinoids, or oral immunosuppressants.

For further information or assistance with contact dermatitis, please contact a medical advisor in your nearest WorkSafeBC office.
—Olivia Sampson, MD, CCFP, MPH, FRCPC, ABPM 
—Lorri Galbraith, MD, MScOH, FCBOM, CIME
WorkSafeBC Occupational Disease Services Medical Advisors

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This article is the opinion of WorkSafeBC and has not been peer reviewed by the BCMJ Editorial Board.

References

1. Rashid RS, Shim TM. Contact dermatitis. BMJ 2016;353:i3299.

2. Adisesh A, Robinson E, Nicholson PJ, et al. UK standards of care for occupational contact dermatitis and occupational contact urticarial. Br J Dermatol 2013;168:1167-1175.

3. Quah CHH, Koh D, How CH, Quah JHM. Approach to hand dermatitis in primary care. Singapore Med J 2012;53:701-704.

4. Fonancier L, Bernstein DI, Pacheco K, et al. Contact dermatitis: A practice parameter-update 2015. J Allergy Clin Immunol Pract 2015;3(3 suppl):S1-39.

5. Nicholson PJ, Llewellyn D, English JS; Guidelines Development Group. Evidence-based guidelines for the prevention, identification, and management of occupational contact dermatitis and urticaria. Contact Dermatitis 2010;63:177-186.

6. Usatine RP, Riojas M. Diagnosis and management of contact dermatitis. Am Fam Physician 2010;82:249-255.