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An evaluation of dermoscopy fluids and application techniques
A J Gewirtzman1, J-H Saurat, R P Braun
1Pigmented Skin Lesion Clinic, Department of Dermatology, University Hospital Geneva, 24, rue Micheli-du-Crest, CH-1211 Geneva 14, Switzerland.
Background:
Dermoscopy, a noninvasive technique used to help physicians better visualize pigmented skin lesions, is becoming widely used by dermatologists. Yet despite its popularity, to our knowledge basic aspects such as the best immersion fluid (IF) to use and proper procedures for applying the IF and dermatoscope have never been the subject of a systematic investigation.
Objectives:
To determine the best techniques for application of IF and the dermatoscope; to discover which IF results in the least amount of air inclusions; to determine which IF provides the best image quality.
Materials And Methods:
This study was divided into three phases. Phase I examined several techniques of taking digital dermoscopic photographs in an attempt to eliminate air bubbles. Phase II tested seven IFs to analyse quantitatively the number of air inclusions for each IF. Phase III investigated these same IFs to judge the image quality for each.
Results:
Phase I: in our hands, the best technique to apply an IF is to use an eyedropper and place the IF directly onto the skin in combination with a 'roll-on technique': the dermatoscope's edge is placed on the skin first and is then rotated until the glass plate lies flat against the skin. Phase II: the alcoholic IF resulted in the least amount of air bubble inclusions (70% ethanol, 90% isopropanol and alcoholic disinfectant), while liquid paraffin (a mineral oil) resulted in the most air bubbles. Phase III: dermoscopic structures were equally clear with alcohols and liquid paraffin, but slightly blurry with ultrasound gel and water.
Conclusions:
Although 90% isopropanol performed slightly better in terms of air inclusions, we prefer to use 70% ethanol in most circumstances because it has the advantage of being odourless, unlike its counterpart. Additionally, ethanol will not stain clothing, does not crystallize on the dermatoscope, disinfects and evaporates immediately (does not need to be wiped off). For certain local considerations, such as dermoscopy on mucosa or the nail, we prefer to use ultrasound gel because it will not flow.
