Evaluation of patch test reactions by evaporimetry and colorimetry

Evaporimetiy in the differentiation of allergic, irritant and doubtful patch test reactions

BACKGROUND/AIMS

The aim is to evaluate, using evaporimetry, the possibility of getting further information supporting clinical reading of allergic, irritant reactions and doubtful patch test reactions.

METHODS

The investigation was carried out on 204 patients (182 female and 22 male, mean age 31.6 years), patch tested routinely as suspects of allergic contact dermatitis. We evaluated 326 reactions (203 allergic, 123 irritant or doubtful).

RESULTS

Mean values pf TEWL were: for the positive allergic reactions, 7.21 (SD, 2.26) at 48 h, 15.77 (SD, 5.50) at 72 h; and for the irritant or doubtful reactions, 7.55 (SD, 1.72) at 48 h, and 5.77 (SD, 1.41) at 72 h. TEWL in the 2 reactions groups at 72 h was significantly different (p<0.01).

CONCLUSIONS

The study shows (i) concordance between the evaporimeter values and the visual score; (ii) at 72 h, the evaporimeter values are increased in the allergic reactions but not in irritant or doubtful reactions; (iii) evaporimetry in the differential diagnoses of patch test reactions was deemed useful.

Photometric assessment of skin colour and lightness using a tristimulus colorimeter: reliability of inter and intra-investigator observations in healthy adult volunteers

The ageing of injuries is an important aspect of forensic medicine, and one which can have significant medico-legal consequences. The sequence and timing of color changes associated with the appearance and disappearance of bruises, as well as the factors which govern this process, have long been a source of controversy. Whilst visual assessment currently remains the easiest and most practical method available to date bruises, it appears unlikely that it can be relied upon to provide an accurate and consistent measure of the age of a bruise. In an ongoing pilot study designed to assess the applicability of colorimetry to the dating of bruises, the Dr. Lange MICRO COLOR tristimulus colorimeter will be used to assess how the color and colour density (lightness) of bruises change over time. The results of a preliminary study are presented, in which the variability of skin colour measurements obtained by different investigators was assessed. Measurements were taken of the same area on the volar surface of the forearm of five volunteers, after having them remain with their arm motionless for a predetermined period of time (2, 5, and 10 min). Four sets of measurements were taken by each investigator over a total period of 3 h. No significant statistical difference was found after the resting time interval of 5 min between the values obtained by the two investigators (P > 0.05). While studies on a much larger population remain to be completed, our initial findings would seem to suggest that the colorimeter is able to provide an objective, quantitative, and relatively consistent measure of skin colour when used by different individuals.