What is the cause and treatment of dermatographism?

Dermographism: Cause and Treatment

Dermographism is caused by mechanical stimulation of the skin leading to mast cell activation and histamine release, and first-line treatment consists of nonsedating H1 antihistamines, which can be increased up to 4 times the standard dose if needed. 1

Pathophysiology

• Dermographism occurs when mechanical stress or friction on the skin triggers mast cell activation, leading to the release of histamine and pro-inflammatory mediators that produce linear wheals along the area of stimulation 1
• This represents a form of physical urticaria characterized by an exaggerated response to physical stimulus 2
• The condition manifests as dermal edema (wheal) and erythema (flare) that typically appears within minutes of scratching or rubbing the skin 3, 1

Clinical Presentation

• Patients develop linear wheals after scratching or friction, with or without angioedema 1
• The lesions are usually pruritic and typically last less than 24 hours 4
• Symptoms can include pruritus, flushing, and urticaria in response to mechanical triggers 3
• A key diagnostic pitfall: reactions to topical products may actually be due to dermographism from rubbing rather than true allergic contact dermatitis 5

Diagnosis

• The gold standard for diagnosis is medical history combined with a provocation test (dermatographic test), where firm stroking of the skin with a blunt object reproduces the linear wheal 1
• Disease control can be assessed using validated tools including the Urticaria Control Test (UCT), Chronic Urticaria Quality of Life questionnaire (CU-Q2oL), and Dermatology Life Quality Index (DLQI) 1

Treatment Algorithm

First-Line Therapy

• Nonsedating H1 antihistamines are the first-line treatment recommended by EAACI guidelines 1
• Standard dosing should be initiated first 1
• If symptoms persist, the dose can be increased up to 4 times the standard dose 1
• Examples of effective second-generation antihistamines include loratadine, cetirizine, and fexofenadine 4

Second-Line Options

• For symptomatic dermographism refractory to H1 antihistamines alone, combination therapy with H1 and H2 antagonists (e.g., chlorpheniramine plus cimetidine) appears effective 4
• H1 and H2 blockers have been shown to control skin symptoms including pruritus, flushing, urticaria, angioedema, and dermatographism 3

Third-Line Therapy

• Omalizumab (anti-IgE monoclonal antibody) can be considered for off-label use when conventional antihistamine therapy fails 3, 1
• Omalizumab has demonstrated particular effectiveness for recurrent anaphylaxis and skin symptoms in mast cell-mediated conditions 3

Alternative Treatments

• Narrowband UVB phototherapy has shown success in small case series for symptomatic dermographism refractory to antihistamines 2
• Other reported options include leukotriene antagonists, cyclosporine, and oral corticosteroids, though evidence is limited 2
• Cromolyn sodium may be effective for cutaneous symptoms, though primarily studied in systemic mastocytosis 3

Important Clinical Considerations

• Avoid triggers: Counsel patients to minimize scratching, friction, and mechanical trauma to the skin 1, 5
• Older first-generation antihistamines (chlorpheniramine, hydroxyzine) are effective but cause significant sedation and anticholinergic effects, making them less desirable than newer agents 4
• When patients report reactions to topical products, consider dermographism from rubbing before diagnosing medication allergy 5
• Repeat open application testing can confirm the safety of previously suspect medications and prevent unnecessary changes in treatment regimens 5
• Current limitations: There is a lack of biomarkers for predicting disease severity, treatment efficacy, and prognosis 1