RESUMO
OBJECTIVE: Classic dermographism refers to the ability of the skin to produce a linear wheal with a scratch pressure of 4,900 gm/cm2. The authors manufactured a dermographometer to have precise and consistent measurement and tested it on different body regions to find the best location. MATERIAL AND METHOD: Twenty two patients with dermographism were enrolled. The pressure was applied to the volar aspect of the left forearm using the dermographometer and to the right forearm by the pen head. Then the pressure was applied to the upper back, abdomen, and shin using the dermographometer. The time onset and size of wheal, erythema and flare were recorded. RESULT: The positive yield at the left forearm by the dermographometer was 72.7% and the positive yield at the right forearm by the pen head was 68.2%. The positive yield of back, abdomen and shin were 68.2%, 68.2% and 13.6%, respectively. CONCLUSION: The dermographometer gave a comparable positive yield in diagnosing dermographism with the pen head and the dermographometer. The volar forearm, back and abdomen are the sensitive areas to produce dermographism while the shin is the least sensitive area. The site of the body that is most appropriate in testing is the forearm as it is easy to approach.