Possible hazard to patients from immersion oil used for epiluminescence microscopy

Dermatoscope as Vector for Transmissible Diseases – No Apparent Risk of Nosocomial Infections in Outpatients

PURPOSE

To determine nonpathogenic and potentially pathogenic bacterial growth isolated from dermatoscopes of dermatologists using oil as contact medium in the daily routine at two outpatient sections in Switzerland.

METHODS

We investigated the microbiologic colonization of dermatoscopes (Dermatoskop Delta 10, Heine Optotechnik, or Dermogeniusbasic, Rodenstock) during routine use in the outpatient sections of the Departments of Dermatology at the University of Basel and Kantonsspital Aarau. 112 swabs (4 from Aarau, 108 from Basel) taken under standardized conditions were microbiologically worked up in the same laboratory. Oil (101) and 63% isopropyl alcohol (11) were used as contact medium.

RESULTS

39 of 112 swabs showed no bacterial growth. 73 of 112 showed growth of nonpathogenic bacteria (skin flora). Additionally to the cultivation of nonpathogenic bacteria, 3 swabs showed growth of oxacillin-sensitive potentially pathogenic Staphylococcus aureus. Of 11 swabs taken after using 63% isopropyl alcohol as a contact medium, 6 revealed no bacterial growth and 5 showed the growth of skin flora.

CONCLUSIONS

The potential risk of nosocomial infection related to the routine use of dermatoscopes in outpatients is small, and the use of oil as a contact medium for dermatoscopy to enhance the optical quality seems to be unproblematic.

An evaluation of dermoscopy fluids and application techniques

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.