The FP recognized that this was a case of allergic contact dermatitis (ACD), based on the clinical presentation. The distribution of the erythema, scale, and post-inflammatory hyperpigmentation was highly suggestive of an ACD to nickel. In this case, the nickel in the patient’s eyeglasses and the snaps on her pants were the culprit. The plaque near the patient’s eye was actually in the shape of the metal on the inside of her glasses.
ACD is a delayed-type hypersensitivity reaction in which a foreign substance comes into contact with the skin and is linked to skin proteins; this forms an antigen complex, leading to sensitization. When the epidermis is re-exposed to the antigen, the sensitized T cells initiate an inflammatory cascade, leading to the skin changes seen in ACD.
Contact dermatitis can sometimes be diagnosed clinically with a good history and physical exam. However, there are many cases in which patch testing is needed to find the offending allergens or confirm the suspicion regarding a specific allergen. The differential diagnosis includes cutaneous candidiasis, impetigo, plaque psoriasis, and seborrheic dermatitis.
Patients with ACD should avoid the allergen that is causing the reaction. In cases of nickel ACD, the patient may cover the metal tab of his or her jeans with an iron-on patch or a few coats of clear nail polish. Fortunately, some jeans manufacturers now make nickel-free metal tabs (eg, Levis’s).
Cool compresses can soothe the symptoms of acute cases of ACD. Localized acute ACD lesions respond best to mid-potency (eg, 0.1% triamcinolone) to high-potency (eg, 0.05% clobetasol) topical steroids. On areas of thinner skin, lower-potency steroids such as desonide ointment can minimize the risk of skin atrophy.
In this case, the FP recommended that the patient get glasses that were nickel free and explained how to avoid the nickel that still exists in some pants. She was also given desonide 0.05% cream to apply to the affected area for symptomatic relief.
Adapted from: Usatine RP, Jacob SE. Rash on eyebrows and periumbilical region . J Fam Pract . 2017;66:45-47.