Trichoscopic structures and patterns
|Description||This chapter describes tricoscopy structuresThis glossary term has not yet been described. and patternsThis glossary term has not yet been described. as seen by dermoscopyThe examination of [skin lesions] with a 'dermatoscope'. This traditionally consists of a magnifier (typically x10), a non-polarised light source, a transparent plate and a liquid medium between the instrument and the skin, and allows inspection of skin lesions unobstructed by skin surface reflections. Modern dermatoscopes dispense with the use of liquid medium and instead use polarised light to cancel out skin surface reflections.|
|Responsible author||N.N. → send e-mail|
|Status update||December 4, 2018|
|Status by||Ralph P. Braun|
This chapter describes tricoscopy structures and patterns as seen by dermoscopy
It has the following subchapters:
|Hair follicle openings||N.N.|
|Perifollicular and interfollicular skin surface||N.N.|
|Normal trichoscopic findings||N.N.|
- 1 Trichoscopic structures and Patterns
- 1.1 1. Hair shafts
- 1.2 2. Hair follicle openings
- 1.3 3. Perifollicular and interfollicular skin surface
- 1.4 4. Blood vessels
Trichoscopic features can be divided into 4 main groups: hair shafts, hair follicle openings, perifollicular epidermis and blood vesselsare the part of the circulatory system, and microcirculation, that transports blood throughout the human body .
1. Hair shafts
- A normal terminal hair are more than 55 µm wide and are uniform in thickness and color .
- The trichoscopic classificationis a general process related to categorization, the process in which ideas and objects are recognized, differentiated, and understood. of hair shaft abnormalities is proposed by Rudnicka et al. .
|Trichoptilosis||Trichoschisis or trichoclasis||Broken hairs||Golf tee hairs|
|Longitudinal splitting of the distal end of hair shaft||A clean transverse fracture across the hair shaft||Irregular transverse fracture across the hair shaft||A hair with a concave distal end|
|Unspecific manifestation of a defect in hair shaft structure||Trichothiodystrophy, secondary to conditions that weaken the hair shaft||Trichotillomania, traction alopecia, alopecia areata, tinea capitis||Specific for Netherton syndrome|
|Pigtail hairs||Coiled hairs||Comma hairs||Corkscrew hairs||Zigzag hairs||Pili torti||Wooly hairs|
|Short, regularly coiled hairs with tapered ends|| Irregularly coiled hairs with a jagged end
When not fully coiled, they may have a hook-like appearance
|Short, comma-like (C-shaped) hairs, homogeneous in thickness and pigmentation||Hairs with multiple twists and coils, forming corkscrew-like structures||Hairs, bent at sharp angles, form zigzag structures||Hairs that are flattened and twisted on their own axis at irregular intervals, usually through an angle of 180°||Hair shafts with waves at very short intervals, giving a crawling snake appearance|
|Alopecia areata||Trichotillomania||Tinea capitis||Tinea capitis||Tinea capitis, alopecia areata||Associated with multiple inherited and acquired hair diseases||Inherited syndromes|
|Continuous Medulla||Interrupted Medulla||Pili annulati||Interrupted (Morse Code-like) hairs|
|Longitudinal white band along the midpart of the hair shaft that covers less than 50% of the hair shaft thickness|| Interrupted longitudinal white band along the midpart of the hair shaft
The band covers less than 50% of the hair shaft thickness
|Hair shafts with transverse light, blurry, whitish bands covering (nearly) the width of a hair||Hairs with multiple thin white bands across the hair shaft|
|Normal||Normal||Hair shafts with transverse light, blurry, whitish bands covering (nearly) the width of a hair||Tinea capitis|
2. Hair follicle openings
"DotsDots are small, round structures of less than 0.1 mm in diameter that have a red color when corresponding to blood vessels; however, when due to melanin, their color ranges from black, brown, to blue-gray depending on the depth and concentration of the melanin in the skin (Tyndall effect)." correspond to hair follicle openings observed in trichoscopic examination .
2.1. Black dotsDots are small, round structures of less than 0.1 mm in diameter that have a red color when corresponding to blood vessels; however, when due to melanin, their color ranges from black, brown, to blue-gray depending on the depth and concentration of the melanin in the skin (Tyndall effect).
Black dots, also known as “cadaverized hairs”, represent pigmented hairs broken or destroyed at scalp level . They are commonly observed in alopecia areata , dissecting cellulitis [4, 5], trichotillomania  and tinea capitis . Black dots may be also detected in chemotherapy-induced alopecia , lichen planopilaris , discoid lupus erythematosusis a chronic skin condition of sores with inflammation and scarring favouring the face, ears, and scalp and at times on other body areas. These lesions develop as a red, inflamed patch with a scaling and crusty appearance. The centre areas may appear lighter in colour with a rim darker than the normal skin. , traction alopecia , traumatic alopecia , androgenetic alopecia [8, 9] and following a laser depilation or trichogram .
2.2. Yellow dots
Yellow dots correspond to follicular infundibula filled with sebum and/or keratotic material . They present as yellow, or whitish, round or polycyclic dots, varied in size and uniformed in colorColor (American English) or colour (Commonwealth English) is the characteristic of human visual perception described through color categories, with names such as red, yellow, purple, or blue., devoid of hairs or containing miniaturized, cadaverized or dystrophic hairs [10-12].
In alopecia areata, yellow dots are characterized by an abundant amount and regular distribution and predominate in long-lasting, inactive disease [3, 13].
The predominance of yellow dots (they are predominantly sebaceous) in the frontal area compared to the occipital area is characteristic for androgenetic alopecia . They correspond to empty follicular openings of follicles in kenogen phase.
In discoid lupus erythematosus, large, dark yellow dots that correspond to wide infundibula filled with keratotic material are observed [1, 5].
Yellow dots, appearing as large "3D" soap bubbles imposed over dark dystrophic hairs are specific for dissecting cellulitis [1, 5].
Sparse yellow dots may also be detected in chronic telogen effluvium [8, 9], traumatic alopecia  traction alopecia , congenital hypotrichoses and kerion celsi .
2.3. Red dots
Red dots correspond to widened infundibula plugged by keratin and surrounded by dilated vesselsThis glossary term has not yet been described. and extravasated erythrocytes . They are characteristic trichoscopic finding for active discoid lupus erythematosus and believed to be a positive prognostic factor .
2.4. White dots
There are two types of white dots.
The classic, big, irregular white dots correspond to areas of perifollicular fibrosis and are observed most commonly in lichen planopilaris .
The small, regular pinpoint white dots represent hair follicle openings and eccrine sweat gland openings and are observed in sun exposed areas and in dark skin phototypes regardless of hair loss .
3. Perifollicular and interfollicular skin surface
In trichoscopyThis glossary term has not yet been described., following perifollicular and interfollicular skin surface abnormalities may be observed: scaling, discoloration, discharge and surface structure.
Epidermal scaling can be divided into perifollicular and diffuse .
Mild diffuse scaling may be observed in healthy persons with dry skinThis glossary term has not yet been described.. White moderate to severe diffuse scaling is detected in psoriasisThis glossary term has not yet been described., discoid lupus erythematosus and contact dermatitisalso known as eczema is a group of diseases that results in inflammation of the skin.. Yellowish moderate to severe diffuse scaling is presented in seborrheic dermatitis, discoid lupus erythematosus and ichthyosis .
White perifillicular, tubular scaling is characteristic for lichen planopilaris. In folliculitis decalvans, yellowish, tubular with collar formation is observed . It needs to be emphasized, that diffuse “scaling” with formation of white perifollicular clusters may be present in monoclonal gammopathy .
Brown areas in trichoscopy may occur in three different patterns.
Honeycomb pattern comprises a homogenous, mosaic or contiguous brown rings. It may be observed in chronically sun-exposed areas of thinning or complete hair loss and the scalp of dark-skinned patients . Perifollicular brown coloration results from perifollicular lymphocytic infiltration  and is commonly detected in androgenetic alopecia, telogen effluvium. It may be presented in up to 10% of hair follicle openings in healthy persons [14, 18]. Scattered brown discoloration is typical feature of discoid lupus erythematosus .
Pink, “strawberry ice cream” areas are characteristic trichoscopic findings of cicatricial alopecia and correspond to early fibrosis .
White areas are common feature of cicatricial alopecia and correspond to late fibrosing process . They may be also observed in epidermal detachment and edema .
Yellow areas are detected in dissecting cellulitis, follicular pustules, dissecting cellulitis and bacterial infections .
Yellow or yellow-red discharge is detected in folliculitis decalvans, bacterial infections, dissecting cellulitis or tinea capitis .
3.4. Surface structure
Starburst patternThis pattern consists of peripheral globules, pseudopods or streaks (or a combination of them), located around the entire perimeter of the lesion hyperplasia results from fibrosis and is characteristic trichoscopic findings of folliculitis decalvans .
4. Blood vesselsare the part of the circulatory system, and microcirculation, that transports blood throughout the human body
1. Rudnicka, L., et al., TrichoscopyThis glossary term has not yet been described. update 2011. J Dermatol Case Rep, 2011. 5(4): p. 82-8.
2. Rudnicka, L., et al., Hair shafts in trichoscopy: cluesEvidence, in an investigation for diagnosisis the identification of the nature and cause of a certain phenomenon. Diagnosis is used in many different disciplines with variations in the use of logic, analytics, and experience to determine "cause and effect". In systems engineering and computer science, it is typically used to determine the causes of symptoms, mitigations, and solutions of hair and scalp diseases. Dermatol Clin, 2013. 31(4): p. 695-708, x.
3. Inui, S., et al., Clinical significance of dermoscopy in alopecia areata: analysis of 300 cases. Int J Dermatol, 2008. 47(7): p. 688-93.
4. Kowalska-Oledzka, E., et al., 'Black dots' seen under trichoscopy are not specific for alopecia areata. Clin Exp Dermatol, 2012. 37(6): p. 615-9.
5. Rakowska, A., et al., Trichoscopy of cicatricial alopecia. J Drugs Dermatol, 2012. 11(6): p. 753-8.
6. Rakowska, A., et al., New trichoscopy findings in trichotillomania: flame hairs, V-sign, hook hairs, hair powder, tulip hairs. Acta Derm Venereol, 2014. 94(3): p. 303-6.
7. Shim, W.H., et al., Dermoscopic approach to a small round to oval hairless patch on the scalp. Ann Dermatol, 2014. 26(2): p. 214-20.
8. Park, J., et al., Trichoscopic Findings of Hair Loss in Koreans. Ann Dermatol, 2015. 27(5): p. 539-50.
9. Karadag Kose, O. and A.T. Gulec, Clinical evaluation of alopecias using a handheld dermatoscopeThis traditionally consists of a magnifier (typically x10), a non-polarised light source, a transparent plate and a liquid medium between the instrument and the skin, and allows inspection of skin lesions unobstructed by skin surface reflections. Modern dermatoscopes dispense with the use of liquid medium and instead use polarised light to cancel out skin surface reflections.. J Am Acad Dermatol, 2012. 67(2): p. 206-14.
10. Ross, E.K., C. Vincenzi, and A. Tosti, Videodermoscopy in the evaluation of hair and scalp disorders. J Am Acad Dermatol, 2006. 55(5): p. 799-806.
11. Chiramel, M.J., et al., Relevance of trichoscopy in the differential diagnosis of alopecia: A cross-sectional study from North India. Indian J Dermatol Venereol Leprol, 2016. 82(6): p. 651-658.
12. Kibar, M., et al., Trichoscopic findings in alopecia areata and their relation to disease activity, severity and clinical subtype in Turkish patients. Australas J Dermatol, 2015. 56(1): p. e1-6.
13. Rudnicka, L., M. Olszewska, and A. Rakowska, Atlas of trichoscopy: dermoscopy in hair and scalp disease. 2012, London: Springer.
14. Rakowska, A., et al., DermoscopyThe examination of [skin lesions] with a 'dermatoscope'. This traditionally consists of a magnifier (typically x10), a non-polarised light source, a transparent plate and a liquid medium between the instrument and the skin, and allows inspection of skin lesions unobstructed by skin surface reflections. Modern dermatoscopes dispense with the use of liquid medium and instead use polarised light to cancel out skin surface reflections. in female androgenic alopecia: method standardization and diagnostic criteriameasure of how well one variable or set of variables predicts an outcome. Int J Trichology, 2009. 1(2): p. 123-30.
15. Inui, S., Trichoscopy for common hair loss diseases: algorithmic method for diagnosis. J Dermatol, 2011. 38(1): p. 71-5.
16. Tosti, A., et al., Follicular red dots: a novel dermoscopic pattern observed in scalp discoid lupus erythematosus. Arch Dermatol, 2009. 145(12): p. 1406-9.
17. Waskiel, A., et al., Trichoscopy of alopecia areata: An update. J Dermatol, 2018.
18. Rakowska, A., Trichoscopy (hair and scalp videodermoscopy) in the healthy female. Method standardization and norms for measurable parameters. J Dermatol Case Rep, 2009. 3(1): p. 14-9.