37.    An evaluation of hair dermatoscopy in assessment of hair shaft abnormalities. 
Marc Wallace, David de Berker, Bristol Dermatology Department, Bristol Royal Infirmary, Bristol, UK.

Examination of hair contributes diagnostic information in a range of adult and paediatric conditions. We have set out to examine the relative merits of transmitted light microscopy and Dermatoscopy in hair shaft microscopy. Typical examples of selected conditions were identified from an extensive collection of scalp hair and examined using a Dermlite Pro HR II dermatoscope and Nikon E200 light microscope, with paired cross- polarising filters. Hair shaft characteristics were photographed using a Nikon Coolpix 4500 digital camera.
Dermatoscopy was helpful in detecting tapered hairs, weathering, monilethrix, pediculosis capitis, peripilar casts, exclamation mark hairs of alopecia areata, bubble hair and pili torti. It was less helpful in pili annulati and unhelpful in detecting ‘tiger-tail’ banding in trichothiodystrophy. Light microscopy provided greater detail in almost all cases. It was necessary for detection of hair cuticle changes and added significantly more information in detecting characteristic features of trichothiodystrophy, pili annulati, bubble hair and pili torti. Dermatoscopy is a useful clinical tool when examining numerous hair conditions. It is most revealing in conditions manifested by gross changes in shaft outline and colour, where reflected light is valuable. It is not helpful for detection of features within the shaft or at higher levels of resolution. When added to its ability to aid evaluation of scalp surface charcacteristics, Dermatoscopy provides an excellent first-line method of assessment of problems in the hair clinic. Use in vivo allows it to be used for screening of areas of scalp in order to select hairs of greatest diagnostic yield for further assessment. In some instances, it may obviate the need for obtaining a hair specimen. Where detailed or cortical hair shaft features need assessment, transmitted light microscopy remains the standard tool.