Introduction
Introduction
Value of trichoscopy
Perifollicular skin
The dermatoscope is a non-invasive diagnostic device that allows better recognition of morphologic structures not visible to the naked eye. Current use of the dermatoscope has widened, and the vast majority of dermatologists and some general practitioners have embraced dermoscopy as the gold standard to differentiate melanoma from other pigmented skin lesions.
Dermoscopy has become valuable in the recognition of non-pigmented skin lesions, as well as inflammatory dermatoses, and trichoscopy is being adopted as a valuable technique in evaluating the hair not only on the scalp but on the brows and hairy areas elsewhere.
Other DermNet pages on trichoscopy include:
Trichoscopy involves examination of the scalp and hair using a handheld or a videodermoscopy device. Examination with a dermatoscope (trichoscope) can reassure patients that they have received a thorough scalp examination and provide the clinician with invaluable in vivo information about scalp and hair shaft pathology.
Videodermoscopy is a new and valuable tool in assessing hair and scalp disorders. Surface and subsurface microscopic views provide a previously unrecognized clinical perspective on disease, features seen with the naked eye are visibly enhanced, and patterns of disease that help in diagnosis are readily visualized.
The images are acquired by computerized polarized-light videomicroscopy using lenses with factors of magnification at 10× increments. Both epiluminescent and non-epiluminescent modes were employed. Alcohol gel is used as the interface solution. Captured images are digitalised and displayed on a high-resolution monitor in real-time. Selected images can be stored on a computer for serial assessment over time.
Trichoscopy represents a valuable, non-invasive and low-cost technique which can be of help in diagnosis of most hair and scalp diseases, allowing visualisation of the hair and scalp at x20 to x160 magnifications.
Images can be recorded digitally either using a separate digital camera connected to the trichoscope, or a built-in digital imaging system.
It can help to distinguish scarring versus non-scarring alopecia, early androgenetic alopecia versus telogen effluvium, and predict prognosis of alopecia areata.
Many studies describe its application in randomly selected patients suffering from hair loss, not only as a diagnostic tool but also in monitoring treatment response. Other uses include guiding selection of the optimum site of scalp biopsy and teledermoscopy for case discussion and second opinions.
Current research is focusing on trichoscopy of:
Trichoscopy allows four basic structures to be recognized:
All structures must be examined thoroughly and any report should include the normal and the abnormal findings as the collective data interpretation leads to a more accurate diagnosis.
Trichoscopy is a useful tool in assessment of the hair follicle condition whether:
Follicular openings are classified according to the following criteria.
A black dot (previously called a cadaverized hair) is a term used to describe a follicular opening which contains remnants of pigmented hairs broken at the scalp level.
Yellow dots represent follicular infundibulae filled with keratin with no hair shafts. They are detected in different cicatricial and non-cicatricial disorders.
Fibrosis following the destruction of hair follicles, such as in lichen planopilaris, appears variable in size and shape and may become confluent forming structureless white areas. In severe alopecia areata, cumulus-like white dots representing confluent fibrosis of follicles are reported.
Red dots were described mainly in discoid lupus erythematosus. Many authors believe that the presence of red dots is a good prognostic factor denoting the possibility of hair regrowth.
Pink dots are occasionally seen in the eyebrow area in patients with frontal fibrosing alopecia.
The normal human hair shaft cross-section is divided into three zones; the medulla, the cortex, and the cuticle, with different variations among races.
The normal hair shafts are uniform in thickness and colour. Using trichoscopy of normal hair shafts, authors describe two types of hair:
Trichoscopy is used widely to detect different hair shaft, shape, and thickness disorders and diagnosis of their causative diseases. Abnormalities of shape can be classified according to the underlying cause:
Abnormalities in hair shaft thickness occur in androgenic alopecia due to miniaturization.
Hair casts represent detached hyperkeratotic and parakeratotic cells of the inner root sheath which surrounds the hair shaft. Different conditions show peritubular casts including:
Examination of perifollicular skin provides significant clues that help in the diagnosis of different scalp disorders. Assessment of scalp texture is helpful to differentiate cicatricial from non-cicatricial alopecias.
Trichoscopic features that may be observed in perifollicular skin include; scales, areas of different colours, discharge, vascular structures, and some others.
Scalp atrophy is a clinical finding that can be confirmed using trichoscopy. In patients with alopecia areata who have received prolonged use of steroid injections, prominent vessels, and visible hair bulbs with ivory-coloured areas (due to the steroid solution excipients) are observed.
Scales are classified according to their distribution into:
Perifollicular skin may show different colours, each suggesting an underlying specific condition.
Yellow and yellow-red discharge is observed in folliculitis decalvans, bacterial infections, dissecting cellulitis, or inflammatory tinea capitis.
In order to examine vascular structures of the scalp, non-contact or videodermoscopy with higher magnification is preferred. Vascular structures detected using trichoscopy are widely variable in morphology and distribution according to the underlying causative disorder.
