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Trichoscopy allows analysis of the structure and size of growing hair shafts.
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With trichoscopy is possible to diagnose most genetic hair shaft defects without the need of pulling hairs for light microscopic evaluation.
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Hair shaft structure abnormalities may provide diagnostic clues for multiple causes of hair loss beyond genetic hair shaft disorders.
Hair Shafts in Trichoscopy: Clues for Diagnosis of Hair and Scalp Diseases
Section snippets
Key points
Trichoscopy is dermoscopy of hair and scalp.1, 2 Among other diagnostic functions, trichoscopy allows analysis of the structure and size of hair
Normal hairs
A normal terminal hair is uniform in thickness and color throughout its length.5, 6 An individual may have hair shafts that differ from each other by color and by thickness. Presence of diversely pigmented hairs is a normal finding in graying persons. In children and young adults, simultaneous presence of dark and gray hairs is rare and may be indicative of vitiligo, ectodermal dysplasia, or another other cause of premature graying.7
The thickness of normal hairs is usually more than 55 μm. Hair
Classification of hair shaft abnormalities in trichoscopy
The authors propose a classification of hair shaft features observed in trichoscopy (Fig. 2). The proposed classification adopts a structure-based approach, also observed in light microscopy,10 wherever applicable. It distinguishes the following groups of hair shaft abnormalities observed by trichoscopy: (1) hair shafts with fractures, (2) hair narrowings, (3) hairs with node-like structures, (4) curls and twists, (5) bands, and (6) short hairs. We consider hairs as short hairs when the entire
Exclamation Mark Hairs
Exclamation mark hairs (exclamation point hairs) are hairs with thin proximal ends and significantly thicker distal ends. Often, the proximal end is hypopigmented, whereas the distal end appears hyperpigmented.11 Exclamation mark hairs, which are 1 to 3 cm long, may be observed with the naked eye and are a well-known feature of alopecia areata.12, 13, 14 With a dermoscope, it is possible to observe exclamation mark hairs that are significantly shorter, usually 1 to 5 mm.15 Thus, some
Trichoclasis and Trichoschisis
Trichoclasis (trichoclasia) and trichoschisis are clean transverse fractures across the hair shaft. There is some confusion in the literature about the exact meaning of these terms. Most investigators use the term trichoclasis to describe hair fractures induced by chemical or physical trauma that develop secondary to conditions that weaken the hair.52, 53 Trichoclasis have been described in otherwise healthy individuals (idiopathic trichoclasis)54 and in patients with alopecia areata.55 In
Summary
Trichoscopy allows evaluation of the hair shaft structure, scalp surface, follicular openings, and superficial blood vessels. This article has summarized how evaluation of hair shaft structure alone may provide clues for differential diagnosis of hair loss.
References (84)
- et al.
Trichoscopy: how it may help the clinician
Dermatol Clin
(2013) Alopecia areata update
Dermatol Clin
(2013)- et al.
How to diagnose hair loss
Dermatol Clin
(2013) - et al.
Alopecia areata update: part I. Clinical picture, histopathology, and pathogenesis
J Am Acad Dermatol
(2010) - et al.
Comma hairs: a dermatoscopic marker for tinea capitis: a rapid diagnostic method
J Am Acad Dermatol
(2008) - et al.
Comma hairs: a new dermoscopic marker for tinea capitis
Actas Dermosifiliogr
(2012) - et al.
Cutaneous findings in a new syndrome of autosomal recessive ectodermal dysplasia with corkscrew hairs
J Am Acad Dermatol
(1992) - et al.
Ectodermal dysplasia with corkscrew hairs: observation of probable autosomal dominant tricho-odonto-onychodysplasia with syndactyly
J Am Acad Dermatol
(1994) - et al.
A case of probable autosomal recessive ectodermal dysplasia with corkscrew hairs and mental retardation in a family with tuberous sclerosis
J Am Acad Dermatol
(1998) - et al.
Videodermoscopy in the evaluation of hair and scalp disorders
J Am Acad Dermatol
(2006)
Structural abnormalities of the hair shaft
J Am Acad Dermatol
Dermatoscopy of hair shaft disorders
J Am Acad Dermatol
Atlas of trichoscopy: dermoscopy in hair and scalp disease
Trichoscopy: a new method for diagnosing hair loss
J Drugs Dermatol
Trichoscopy update 2011
J Dermatol Case Rep
Trichoscopy
Arch Dermatol
Trichoscopy (hair and scalp videodermoscopy) in the healthy female. Method standardization and norms for measurable parameters
J Dermatol Case Rep
Biology of the hair follicle
Pharmacologic interventions in aging hair
Clin Interv Aging
Effective treatment of female androgenic alopecia with dutasteride
J Drugs Dermatol
Hair medulla morphology and mechanical properties
J Cosmet Sci
Light microscopy of the hair: a simple tool to “untangle” hair disorders
Int J Trichology
Trichoscopy for common hair loss diseases: algorithmic method for diagnosis
J Dermatol
Alopecia areata
Videodermatoscopy enhances diagnostic capability in some forms of hair loss
Am J Clin Dermatol
Clinical significance of dermoscopy in alopecia areata: analysis of 300 cases
Int J Dermatol
Treatment of severe alopecia areata with intralesional steroid injections
J Drugs Dermatol
Videocapillaroscopic pattern of alopecia areata before and after diphenylciclopropenone treatment
Int J Immunopathol Pharmacol
Diagnostic value of exclamation mark hairs
Dermatology
Photoletter to the editor: the Friar Tuck sign in trichotillomania
J Dermatol Case Rep
Exclamation marks and other trichoscopic signs of chemotherapy-induced alopecia
Australas J Dermatol
Acute alopecia: clue to thallium toxicity
Pediatr Dermatol
The coudability sign of alopecia areata: the real story
Clin Exp Dermatol
Coudability hairs: a revisited sign of alopecia areata assessed by trichoscopy
Clin Exp Dermatol
Utility of dermoscopy in alopecia areata
Indian J Dermatol
Dermoscopic pattern in tinea capitis
Rev Iberoam Micol
Corkscrew hair: a new dermoscopic sign for diagnosis of tinea capitis in black children
Arch Dermatol
Comma hairs in tinea capitis: a useful dermatoscopic sign for diagnosis of tinea capitis
Pediatr Dermatol
Tinea capitis mimicking folliculitis decalvans
Mycoses
Alternaria scalp infection in a patient with alopecia areata. Coexistence or causative relationship?
J Dermatol Case Rep
Dermoscopic corkscrew hairs dissolve after successful therapy of Trichophyton violaceum tinea capitis: a case report
Australas J Dermatol
Be vigilant for scurvy in high-risk groups
Practitioner
Cited by (79)
[Translated article] Trichoscopy in Alopecia Areata
2023, Actas Dermo-SifiliograficasKeys to the diagnosis of hair shaft disorders: Part I
2022, Actas Dermo-SifiliograficasKeys to the Diagnosis of Hair Shaft Disorders: Part II
2022, Actas Dermo-SifiliograficasDermoscopy of skin infestations and infections (entomodermoscopy) – Part II: viral, fungal and other infections
2021, Anais Brasileiros de DermatologiaCitation Excerpt :They are described in ectothrix-type fungal infections, with an incidence of 5% to 49% (mean 21%).26 In addition to being seen in tinea capitis, they can also be seen in alopecia areata.27 Among other findings that can also be seen on trichoscopy of tinea capitis, but which are not characteristic, broken hairs, black dots, and inter and perifollicular desquamation can be highlighted.26
The trichoscopic features of hair shaft anomalies induced by epidermal growth factor receptor inhibitors: A case series
2021, Journal of the American Academy of DermatologyCitation Excerpt :We did not observe the 180° twist along the shaft axis at the areas of this fusiform pigmentation, and therefore we assume that this phenomenon is not a form of exaggerated pili torti. Although there were a few points with atypical brush-like ends of hair (fractured and frayed ends), we did not observe clear full findings indicating that this phenomenon is in the spectrum of trichorrhexis nodosa (no white nodes along the hair shaft with breaking at these points were observed).11 EGFR ligands, including EGF and transforming growth factor alpha, play a critical role during the hair cycle, triggering the anagen (growth) and catagen (transition) phases (EGFR mediates the termination of the anagen phase).2,17
Authors have no conflict of interest.