Dermographism

Specialty: Skin.

• dermographic urticaria
• writing on the skin
• autographism

Why it occurs

• Inappropriate local release of histamine by dermal mast cells upon application of shear force or mild mechanical friction to the skin
• Idiopathic or simple primary dermographism (physiological variant present in a significant percentage of the healthy population)
• Basic subclinical infections (intestinal parasitosis, chronic streptococcal tonsillitis)
• Subclinical adverse reactions or prodromal phase of reactions to medications (penicillins, anti-inflammatories)
• Emotional disorders or acute psychological stress that sensitizes mast cell degranulation.

Initial workup

Diagnostic skin provocation test using a dermographometer or applying controlled firm pressure with a blunt-tipped object (such as a tongue depressor) to the patient's back to observe the formation of a linear pruritic, erythematous wheal over a period of 5 to 10 minutes. Control analysis with complete blood count, total immunoglobulin E (IgE), and parasitological examination if symptomatic.

Standard management

• Cetirizine — first-line non-sedating second-generation H1 antihistamine, dose of 10 mg daily orally to suppress the response to mechanical friction
• Fexofenadine — non-sedating antihistamine alternative with a broad safety profile, dose of 180 mg daily orally
• Famotidine — H2 antihistamine added in combination in refractory cases to enhance dermal histaminergic blockade, dose of 20 to 40 mg daily
• Hydroxyzine (sedative H1 antihistamine useful for symptomatic control if pruritus interferes with sleep, dose of 25 mg at night).