The use of this technique provides a valuable aid in diagnosing pigmented skin lesions; hair disorders, inflammatory and others skin diseases. Dermatoscopic evaluation shows specific or non specific pattern of diseases which can be co-related with clinical history and examination to reach final diagnosis.

Need for dermatoscope is not a novel approach in dermatology. Hand lens has been used by dermatologist from hundreds of years for the same purpose. Dermatosope has advantage for having image proof with better resolution thus becomes the essential instrument in dermatology clinic. Commercially different types of dermatoscope are available and one has to be wise in purchasing the device.

Types of device: – (a) The dermatoscope: – It is the simplest and best-recognized piece of equipment used to perform a dermoscopy examination. It is easy to operate with minimal technical support.  The price varies according to manufacturing companies, types of device, power of lens used and use of assisting device. A dermatoscope can be connected with anything among TV monitor, computer, camera, mobile or USB device.  Power of lens varies among dermatoscope, 50-200x magnification is sufficient enough for routine clinical practice.

Components: – Achromatic lens, Inbuilt illuminating system, Power supply, image analyzer.

 (b) Stereomicroscope: – It allows an accurate binocular observation with different magnifications (X6-80). The illumination system includes a halogen lamp (12 V/50 W). The stereomicroscope is expensive, large and bulky. It is not indicted for routine clinical practice and only advantage is of better visualisation then dermatoscope.

The videodermatoscope include a polarized or nonpolarized video probe that transmits images of the skin lesion to a color monitor.

Nonpolarized v/s polarized light.

The polarized system allows a better visualization of vessels and red areas. Nonpolarized dermoscopy requires the application of a liquid or a gel in the interface between the instrument and the skin surface. Furthermore, the study of vascular pattern may be compromised by excessive pressure of the instrument resulting in compression of vessels. Thus, vascular patterns cannot properly be examined in their real shape. On the other hand, structures such as pseudocysts, multiple gray-blue dots and blue-white veil are more accurately evaluated by non polarized dermoscopy.

Indications:

1.      Hair and scalp disorder- Dermatoscopy or trichoscopy helps in visualisation of hair shaft, texture, cuticle, hair follicle opening, cutaneous microvessels,  intrafollicular, interfollicular and perifollicular skin changes. Congenital hair shaft abnormalities like as monilethrix, trichorrhexis nodosa, trichorrhexis invaginata, pili torti or pili annulati are more evident on dermoscopy. Acquired hair shaft abnormalities;- micro-exclamation mark hairs, tapered hairs and tulip hairs (in alopecia areata and trichotillomania), regrowing upright or pigtail hairs (in various diseases), comma hair or corckscrew hairs (in tinea capitis). Both scarring and non scarring allopecia can be easly differentiated and at times reduce the need for scalp biopsies.  Trichoscopy also allows use for assessing the number of hairs in one follicular unit. In healthy individuals 2-3 hairs emerge from one follicular unit. The number is decreased in non-cicatricial alopecia and increased above 4 in tufted folliculitis, folliculitis decalvans or lichen planopilaris.

Dermoscopy can also be used for prognosis of scalp disorders following treatment. Hair shaft number per follicle, thickness of hair and interfolliclar distance, all can be measured and compared further with the use of dermatoscope.

2.   Pigmentory disorder:–  Dermoscopy helps in visualisation of by specific or nonspecific pattern of pigmented skin disorder. The identification of specific diagnostic patterns related to the distribution of colors and dermoscopy structures can better suggest a malignant or benign pigmented skin lesion. There are specific and non-specific guide criteria for pigmentory skin disorder. Specific guide criteria are further classified as primary and secondary criteria.

Primary guide criteria: – pigment network, pseudopigmneted network, radial streaming and pseudopodes, pigmented globules.

Fig 3. A. pigment network (melanoma), B. radial streaming (melanoma),

C. Pseudopodes (melanoma) , D. pigmented globules (melanocytic neavus).

(adapted from [4]).

Secondary criteria: – Pigmented dots, blue-white veil, blue grey areas, steel blue areas, depigmnetation.

Secondary criteria: – Pigmented dots, blue-white veil, blue grey areas, steel blue areas, depigmnetation.

Conclusion:- 

Among all the dermatological disorder, majority of them rely on careful observation and examination with naked eye. Dermatoscope enhance the optical resolution with image proof of skin disorder thus helps in diagnosing and  further evolution of skin disorder. Several dermatoscopes are available in market and choice should be made on power of lens, image quality, polarized and/or nonpolarized light, assisting device like mobile, computer, and camera. Many research article been published recently and has become area of interest for dermatologist. More research is required for the best use of dermoscope.

1.     Sar-Pomian M, Kurzeja M, Rudnicka L, Olszewska M, The value of trichoscopy in the differential diagnosis of scalp lesions in pemphigus vulgaris and pemphigus foliaceus. An Bras Dermatol. 2014;89(6):1007-12.

2.      Francesco Lacarrubba, Anna Elisa Verzì and Giuseppe Micali*. Dermatoscopy and Video Dermatoscopy in the Diagnosis and Therapeutic Monitoring of Plaque Psoriasis: A Review.  2014; 1(6).

3.     Lidia Rudnicka, Małgorzata Olszewska, Adriana Rakowska, Monika Slowinska. Trichoscopy update 2011. J Dermatol Case Rep 2011 4, pp 82-88.

4.     Ignazio Stanganelli, Maria Antonietta Pizzichetta, Dermoscopy; www.http://emedicine.medscape.com/article/1130783-overview;