Parâmetros inflamatórios do teste cutâneo por puntura determinados por fotografia digital e termometria cutânea* Evaluation of skin prick test using digital photography and skin infrared thermography

Objective: The present study was to apply the digital photography and skin termography for objective evaluation of prick test. Methods : Histamine and Dermatophagoides pteronyssinus was used on the forearm of volunteers with different phototypes. The camera was held at a fixed distance and digital photos of wheal and flare were obtained at 0, 3, 5, 10,15 and 20 min. All pictures were stored and data determined by Adobe Photoshop ® . Briefly, a circle with a known area was used for size reference. The wheal area was determined by several filter masks and selected by the magic wand tool of the software. Basic colors intensity and brightness of the flare were compared to that of a normal skin area. Results: The computer analysis of the wheal size obtained showed the increase these values with maximum point between histamine and allergen at 10 min (27,47 and 30,7 mmm 2 ). Regarding color intensity, the red color varied significantly during the reaction. Intensity of red varied from 0,38 ± 2,57 to 8,26 ± 3,48 at 10 min (p<0.001). However, the green color reduced over time. The skin temperature increased during 20 min. Similar data were observed with increased of the wheal size. Conclusions : The digital photography has allowed an objective method for evaluation of skin test reactions. The intensity of erythema and the increase of temperature looks like the increase of the wheal size.