Big word, important concept – Dermatographism

Big word, important concept – Dermatographism

Dermatographism is a term that comes from Greek and Latin words dermos (skin) and graphia (to write). It literally means to write in the skin and thus, describes an exaggerated cutaneous response to physical stimuli in the form of hives.

The physiologic mechanism is histamine degranula-tion from mast cells in the skin by mechano-immuno-logic triggers. Thus, systems of burning, itching, redness and welting occur from pressure such as tight clothing, belts and bra straps.

Stroking the skin or scratching can also lead to symptoms, as can continuous pressure such as sitting (on your buttocks) or standing (on your feet).

There are some subtypes of dermatographism such as the cholinergic form. This form is worse when the body is heated as from exercise, a hot shower or a fever. Follicular dermatographism tends to center around hair follicles and manifests as several papules rather than larger welts.

White dermatographism is, as the name implies, blanching of the itchy skin rather than redness, and is due to vasoconstriction (blood vessel narrowing). Cold-dependent dermatographism requires cold exposure.

Dermatographism can be primary (inherited) or secondary. Secondary can be systemic disease-induced such as hyperthyroidism, diabetes and mastocytosis; drug-induced as in allergic reactions (especially to amoxicillin, cephalosporins, atorvastatin and famotidine); from infectious triggers (this is especially common in children with strep infections and viruses), and from psychological factors such as stress and anxiety.

The mainstay of treatment is antihistamine drugs. Usually a combination of a histamine one (H1) receptor blocker and a histamine 2 (H2) receptor blocker is required. A combo that often works well is Zyrtec (H1) and Zantac (H2).

In more severe cases a third drug can be added – a leukotriene modifier (Singulair or Accolate). Also, phototherapy using narrow-band UVB has been shown to be helpful.

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