From the Guidelines
Patch testing is not typically used for diagnosing irritant contact dermatitis (ICD), as it is specifically designed to identify allergic contact dermatitis by detecting delayed hypersensitivity reactions to specific allergens. The diagnosis of irritant contact dermatitis is usually made clinically based on the patient's history of exposure to known irritants, the pattern and appearance of the dermatitis, and the exclusion of other causes 1. According to the British Association of Dermatologists' guidelines for the management of contact dermatitis 2017, patch testing should be offered for patients with chronic or persistent dermatitis as clinical features alone are unreliable in distinguishing allergic contact from irritant and endogenous dermatitis, particularly with hand and facial dermatitis 1.
Key Points to Consider
- Irritant contact dermatitis is caused by direct damage to the skin from chemicals, physical agents, or environmental factors rather than an immunological response.
- The management of irritant contact dermatitis focuses on identifying and avoiding the causative irritant, restoring the skin barrier with moisturizers, and using topical corticosteroids for inflammation when needed.
- Patch testing may be performed to rule out allergic contact dermatitis if a patient presents with dermatitis that could be either irritant or allergic in nature, but a negative patch test in the presence of persistent dermatitis would support a diagnosis of irritant contact dermatitis 1.
Clinical Assessment and Patient Counselling
It is essential to use clinical assessment tools such as the Dermatology Life Quality Index and the Hand Eczema Severity Index for both the initial assessment and the response to treatment of patients with contact dermatitis, as recommended by the British Association of Dermatologists' guidelines 1. Additionally, providing a patient information leaflet on patch testing as part of the counselling process, which includes information on potential side-effects, and obtaining informed patient consent is crucial 1.
From the Research
Patch Testing in Irritant Contact Dermatitis
- Patch testing is primarily used to diagnose allergic contact dermatitis (ACD) 2, 3, 4, 5.
- It is not typically used to diagnose irritant contact dermatitis (ICD), as ICD is not immunologically mediated 3, 6.
- ICD is often diagnosed by exclusion, with patients undergoing testing to rule out type I and type IV hypersensitivity 6.
- Management of ICD consists of irritant identification and avoidance, with regular emollient use 6.
- While patch testing may not be directly relevant for ICD, it can be useful in cases where both ACD and ICD are suspected, or when the diagnosis is unclear 2, 5.
Key Considerations
- The distribution of the presenting dermatitis can provide insight into potential causative allergens and should be taken into account when selecting patch test allergens 5.
- Determining the clinical relevance of patch test results is a critical component of the patch testing procedure 5.
- Patients must be educated on avoidance of relevant allergens and given guidance on alternative products available for use 5.