Definition of Dermoscopy
Dermoscopy (dermatoscopy, epiluminescence microscopy [ELM], incident light microscopy, skin surface microscopy) is a non-invasive diagnostic technique for the in vivo observation of pigmented skin lesions, allowing a better visualization of surface and subsurface structures. This diagnostic tool permits the recognition of morphologic structures not visible by the naked eye, thus opening a new dimension of the clinical morphologic features of pigmented skin lesions.

The Technique
The technique consists in placing mineral oil, alcohol or even water on the skin lesion that is subsequently inspected using a hand-held lens, a hand-held scope (also called dermatoscope), a stereomicroscope, a camera, or a digital imaging system. The magnifications of these various instruments range from 6x to 40x and even up to 100x. The widely used dermatoscope has a 10-fold magnification permitting a sufficient assessment of pigmented skin lesions in daily routine. The fluid placed on the lesion eliminates surface reflection and renders the cornified layer translucent, thus allowing a better visualization of pigmented structures within the epidermis, the dermoepidermal junction and the superficial dermis. Moreover, size and shape of vessels of the superficial vascular plexus can be easily appreciated by this procedure. 
Nowadays dermoscopy is widely used, especially in European countries, by all physicians managing pigmented skin lesions, and particularly by dermatologists. Most of them use the traditional dermatoscope, but a growing number are already equipped with digital imaging systems.

Significance of Dermoscopy
Previous studies demonstrated that dermoscopy improves accuracy in diagnosing pigmented skin lesions. Reports assessing diagnostic accuracy by clinical examination have shown that dermatologists are able to detect melanoma in 65-80% of cases. depending on their expertise [Grin 1990, Miller and Ackerman 1992, Wolf 1998]. In a recent systematic review of accuracy in diagnosing melanoma, dermoscopy has been reported to allow 10-27% higher sensitivity than clinical diagnosis by the naked eye [Mayer 1997].
However, it has been clearly shown by Binder et al. [J Am Acad Dermatol 1997] that when using dermoscopy clinicians may improve their diagnostic performance only if trained formally. Also in our estimation, formal training is crucial for the useful and competent application of this technique.

References
1. Grin CM, Kopf AW, Welkovich B, Bart RS, Levenstein MJ. Accuracy in the clinical diagnosis of malignant melanoma. Arch Dermatol 1990;126:763-766. 2. Mayer J. Systematic review of the diagnostic accuracy of dermatoscopy in detecting malignant melanoma. Med J Aust 1997;167:206-210.	3. Miller M, Ackerman AB. How accurate are dermatologists in the diagnosis of melanoma? Degree of accuracy and implications. Arch Dermatol 1992;128:559-560. 4. Wolf IH, Smolle J, Soyer HP, Kerl H. Sensitivity in the clinical diagnosis of malignant melanoma. Melanoma Res 1998;8:425-429.