Description

Dermagraphism (dermatographism) involves the production of a wheal and flare reaction in the skin by physical stroking or rubbing. Affected patients may be able to make patterns or letters on their skin by running a blunt stylus across the skin surface.


 

Kobner's phenomonen is the occurrence of cutaneous reactions at sites of rubbing or pressure.

 

Clinical classification:

(1) simple (asymptomatic)

(2) symptomatic, associated with moderate to severe pruritus

 

Types based on onset after stimulus:

(1) immediate (onset within 2-10 minutes)

(2) intermediate (onset in 30 to 120 minutes)

(3) late onset or delayed (onset in 4 to 6 hours)

 

Etiologic classification:

(1) primary

(2) secondary, associated with extrinsic factor (drug-induced, insect bites, scabies)

(3) secondary, associated with cutaneous mastocytosis

 

Exacerbating factors:

(1) hot bath

(2) exercise

(3) emotion

(4) cold exposure

 

Technical points:

(1) For monitoring a patient over time, a dermatographometer should be used, since this can monitor the amount of pressure required to produce a reaction.

(2) A standard and reproducible mark should be made, typically 10 cm in length.

(3) The same challenge area on the forearm or back should be used.

 


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