Dermoscopy, considered as the dermatologist's stethoscope in recent times, is an ex vivo noninvasive method which enables us to look beyond what our naked eyes cannot perceive. It helps in examining the subsurface features of the skin and in appreciating the epidermal and superficial dermal features of a lesion at a greater magnitude by decreasing the scattering of light and increasing transillumination, either through polarized light or through usage of a linkage fluid. Therefore, it serves as an important diagnostic aid in the practice of dermatology.
There are three ways to perform dermoscopy:
- Nonpolarized dermoscopy—requires direct contact with the skin surface in addition to a liquid interface (mineral oil or alcohol) placed between the dermoscope and the skin.
- Polarized contact dermoscopy.
- Polarized noncontact dermoscopy.
Polarized dermoscopy has the advantage of eliminating the reflected light from the skin surface by using cross-polarized filters, thus allowing the reflected light from deeper layers to reach the observer's retina, making visualization of structures below the stratum corneum possible.
A few extra minutes is what the dermoscope demands and henceforth the clinical examination stands complete. Apart from enhancing the subtle clinical features, the dermoscope gives an insight into the pigment network as well as the vascular pattern of the skin. Any alteration in them can be very well-detected through a dermoscope, thereby, contributing to the diagnosis. Dermoscopy improves the clinician's diagnostic accuracy and can help correctly classify numerous skin lesions based on the presence or absence of specific dermoscopic structures. Dermoscopy also helps in monitoring the response to treatment and in predicting the prognosis of a disease.
The wide array of colors that we see through a dermoscope actually corroborates to the histology of the normal or diseased skin. Pin-point white dots represent eccrine gland/hair follicles openings while white patches, white shiny structures denote fibrosis. Red color denotes cutaneous vessels and extravasated blood. Superficial cutaneous vessels that form hair pin loops and are perpendicular to the skin appear as dots and globules while the subpapillary plexus which is parallel to the skin appear as red linear structures. Black, light to dark brown, grey, and blue relate to melanin at different depths in the skin. Therefore, the color concept, the different size and shapes in which the colors are configured give rise to various patterns. A constellation of these features contribute to the dermoscopic diagnosis of various skin diseases. For example, the arrangement of red dots in a lesion can differentiate psoriasis from lichen planus and eczema, which actually corresponds to the morphology of different vascular arrangement histologically.
Even the inflammatory infiltrate gives rise to different colors. Orange-yellow background or structures on dermoscopy points toward a granulomatous infiltrate while a violaceous hue usually corresponds to a lichenoid infiltrate.
The pediatric population constitutes a special population in our society with very specific needs. The practice of pediatric dermatology differs greatly from general dermatology since the challenges faced are diverse ranging from inability of the child to correctly specify their problems to handling them in a hospital setup. Handling parental queries and anxieties also form one of the corner stones of pediatric practice. As dermoscopy is a noninvasive and painless tool, it is very well accepted by children and their parents. The ease with which it can be handled and the minimum time required for examination of lesions under a dermoscope, makes it an ideal tool for examining pediatric skin lesions in day-to-day practice. Dermoscopy definitely contributes to the overall satisfaction of the parents as4 it imparts the idea in their mind that a proper thorough examination of their child has been carried out and this in turn improves the doctor-patient relationship as well as compliance.
It is very difficult to perform biopsies in a child because of their low-pain threshold and is often very restless. Moreover, even the parents are hesitant to let their child undergo such invasive procedures. Therefore, it is always better to avoid such procedures in a child and this is where dermoscopy come into play.
Hair disorder in children is very common and raises substantial amount of concern in the parents as well as children. The most common sign is alopecia and can be either due to congenital or acquired causes and the pathology can involve either the hair itself or the scalp skin. Trichoscopy is considered to be as reliable as microscopy in the detection of most hair shaft diseases and thus assist in the diagnosis of multiple genetic disorders, such as trichorrhexis invaginata, trichorrhexis nodosa, monilethrix, pili torti, and pili annulati. Prompt diagnosis of these features with the help of dermoscopy can give the clinician an insight into a broader syndrome, for example, the presence of trichorrhexis invaginata points toward the diagnosis of Netherton's syndrome. Presence of corkscrew and comma hair, exclamation mark hair, flame hairs, and carpet of vellus hair can point toward the diagnosis of tinea capitis, alopecia areata, trichotillomania, and congenital triangular alopecia respectively in cases of patchy hair loss. Trichoscopy is a practical, painless, and tolerable method for examining various hair disorders, obviating the need for plucking or cutting the hair for microscopic examination.
Many dermatological diseases involve the nails in children. Dermoscopy of the nail, i.e., onychoscopy, helps in differentiating onychomycosis from nail psoriasis and nail lichen planus. Visualization of the nail fold capillaries helps in the diagnosis and prognostication of various connective tissue diseases in children.
Dermoscopy is indeed a revelation in the practice of pediatric dermatology. With the ever increasing horizons of dermoscopy literature we are soon progressing to a stage where many skin conditions can be diagnosed with a dermoscope, thus obviating the need for histopathological examination and making it an indispensable tool in our daily practice.