Chapter 4 — Trichoscopy Basics

GP-Level Analogy

"Trichoscopy is to the trichologist what the stethoscope is to the cardiologist — it takes something invisible to the naked eye and makes it unmistakable. A £30 dermatoscope clips onto your smartphone and turns a guessing game into a pattern-recognition exercise."

Trichoscopy is the application of dermoscopy to the scalp and hair. Introduced formally by Rudnicka et al. in 2008, it has since become the single most impactful non-invasive tool in trichology. At 10–20× magnification, features invisible to the naked eye — follicular ostia, hair shaft calibre variation, perifollicular scale, vascular patterns — become instantly readable.

For the GP, trichoscopy offers three practical advantages: it narrows the differential diagnosis before investigations, it reveals active inflammation that physical examination misses, and it allows monitoring of treatment response over time without biopsy.

What trichoscopy reveals

Hair shaft

Shaft morphology

Calibre variation, miniaturisation, breakage, torsion, beading, exclamation mark hairs, comma hairs.

Follicle

Follicular units

Number of hairs per unit, presence/absence of ostia, peripilar casts, yellow/black dots in follicular openings.

Scalp

Perifollicular changes

Erythema, scale pattern, fibrosis (white areas), vascular patterns, honeycomb pigmentation.

Equipment needed

A handheld dermatoscope with polarised light (10× preferred; 20× for detail). Smartphone-attachable models (£30–80) are adequate for GP-level trichoscopy. No gel required with polarised dermatoscopes. Contact dermoscopy with alcohol gives best follicular detail for scalp work.

Studies demonstrate that trichoscopy increases diagnostic accuracy for common alopecias from approximately 70% (naked eye) to over 90% in experienced hands. For the GP, even basic pattern recognition — is there miniaturisation? are follicular ostia present? — fundamentally changes the diagnostic and management pathway.

How to perform trichoscopy

Fig 4.1 — Trichoscopy technique: five-step sequence

Fig 4.1: Five-step trichoscopy technique. Always compare two zones — the diagnostic finding is often the difference between affected and unaffected scalp, not an absolute finding in isolation.

Contact vs non-contact dermoscopy

Mode	Technique	Best for	Limitation
Non-contact (polarised)	Device held 1–2mm above scalp; no interface needed	Quick overview, any hair length	Slightly less follicular detail
Contact (with alcohol)	Alcohol pressed to scalp; hair parted	Vascular pattern, follicular ostia detail	Requires alcohol; slightly uncomfortable
Contact (with gel)	Ultrasound gel as interface	Best follicular detail, shaft examination	Difficult in thick hair; gel residue

GP Practical Tip

For a first trichoscopy encounter, use a polarised (non-contact) dermatoscope. Part the hair at the area of complaint, place the lens perpendicular to the scalp, and compare that zone with the occipital scalp. This single comparison answers the most important question: is there differential miniaturisation or follicular loss?

Core trichoscopy findings

Trichoscopy findings are divided into four groups: hair shaft findings, dot patterns, perifollicular findings, and vascular patterns. Each group has disease-specific patterns that allow rapid diagnosis.

Group 1 — Dot patterns (the most diagnostically powerful group)

Y

Yellow dots

AA · Advanced AGA

Empty follicles filled with sebum/keratin

B

Black dots

AA · Tinea · TTM

Hairs broken at scalp level

W

White dots

Scarring alopecia

Fibrosis replacing follicular units — URGENT

R

Red/Pink dots

DLE · Folliculitis

Dilated infundibula with inflammation

Fig 4.2 — Hair shaft patterns in trichoscopy (schematic)

Fig 4.2: Schematic of six hair shaft patterns seen on trichoscopy. The exclamation mark hair is pathognomonic of alopecia areata; comma and corkscrew hairs are characteristic of tinea capitis; flame/tulip hairs point to trichotillomania.

Group 2 — Perifollicular findings

Finding	Appearance	Diagnosis	Urgency
Peripilar cast (sleeve)	Tubular white/grey scale climbing proximal hair shaft	Lichen planopilaris, FFA	Urgent — active scarring
Perifollicular erythema	Pink/red halo around follicular opening	LPP, FFA, early active AA	Urgent if scarring features
Perifollicular fibrosis	White sheath surrounding follicle	End-stage LPP, FFA, DLE	Irreversible — refer
Honeycomb pattern	Regular pigmented hexagonal network	Normal in darker skin; AGA (relative)	Context-dependent
Targetoid pattern	Central white area, brown ring at follicular opening	Androgenetic alopecia	Non-urgent
Diffuse scale flakes	Large flat white flakes, not follicle-bound	Seborrhoeic dermatitis, psoriasis	Non-urgent

Group 3 — Vascular patterns

Pattern	Description	Diagnosis
Arborising vessels	Tree-like branching red vessels across scalp	Discoid lupus erythematosus (DLE)
Simple red loops	Small looped vessels at follicular openings	Alopecia areata (active)
Twisted red loops	Irregular twisted vessels perifollicularly	Psoriasis, seborrhoeic dermatitis
Glomerular vessels	Tortuous, glomerular-shaped vessels	Psoriasis (classic)
White/avascular areas	No vessels; white structureless zones	Scarring alopecia (burnt-out, fibrotic)

White dots = scarring — act now

On trichoscopy, white structureless areas replacing follicular openings represent fibrotic replacement of the follicle. This finding in any alopecia pattern indicates irreversible scarring. Refer to dermatology urgently — every week of delay means further permanent follicular loss.

Trichoscopy pattern atlas

The following illustrated panels represent the characteristic trichoscopy appearance of the six most common alopecia presentations.

Androgenetic alopecia (AGA)

Non-scarring

Hair calibre diversity: thick terminal + thin miniaturised hairs. Peripilar brown halo (targetoid sign). Yellow dots in advanced cases.

Alopecia areata (AA)

Non-scarring

Yellow dots (empty follicles with sebum) are the hallmark. Black dots at patch margin. Exclamation mark hairs (narrow base, dark tip) at active edge.

Lichen planopilaris (LPP)

SCARRING — urgent

White dots replacing follicular openings (fibrosis). Perifollicular cast — tubular scale climbing the proximal shaft. Perifollicular erythema in active disease.

Tinea capitis

Non-scarring

Comma hairs (short, curved, C-shaped) and corkscrew hairs are pathognomonic. Black dots (broken intrafollicular hairs). Mainly in children.

Trichotillomania

Non-scarring

Flame hairs (tapered, frayed distally), tulip hairs (dark tulip-shaped tip), coiled hairs, hairs broken at different lengths. No yellow dots distinguishes from AA.

Discoid lupus (DLE)

SCARRING — urgent

Red/pink dots (dilated infundibula with inflammatory infiltrate) and arborising vessels. Follicular plugging and keratotic scale. Scarring in chronic disease.

Diagnosis by trichoscopy pattern

The following table integrates hair shaft findings, dot patterns, and perifollicular findings for the six most common alopecias.

Fig 4.3 — Trichoscopy diagnostic matrix

Fig 4.3: Trichoscopy diagnostic matrix for the six most common alopecias. Rows marked YES for scarring (LPP/FFA and DLE) require urgent dermatology referral.

Quick recall — mnemonics

Dot colours: YBWR

Y·B·W·R

Yellow = AA, advanced AGA (sebum/keratin)
Black = AA, tinea, trichotillomania
White = scarring (fibrosis) → refer urgently
Red/pink = DLE, folliculitis (inflamed)

Shaft patterns: MECT

M·E·C·T

Miniaturisation = AGA (calibre diversity)
Exclamation mark = AA (pathognomonic)
Comma + corkscrew = tinea capitis
Tulip/flame = trichotillomania

Perifollicular: CPFH

C·P·F·H

Cast (peripilar sleeve) = LPP, FFA
Perifollicular erythema = active inflam.
Fibrosis (white sheath) = end-stage scar
Honeycomb = AGA / normal dark skin

Scarring red flags: WACF

W·A·C·F

White dots in perifollicular area
Absent follicular ostia
Cast on proximal hair shaft
Fibrotic texture on palpation
Any one = urgent referral

GP quick-reference card

What you see	Think first	Confirm with	Action
Calibre diversity + miniaturisation, quiet scalp	AGA	Clinical + family history	Counsel; offer treatment
Yellow dots + black dots + exclamation hairs	Alopecia areata	Clinical; autoimmune screen	Treat or refer
White dots + absent ostia + peripilar cast	LPP or FFA (scarring)	Biopsy to confirm	Urgent referral
Comma + corkscrew hairs + yellow scale	Tinea capitis	Mycology swab	Systemic antifungal
Flame/tulip hairs + varied breakage + no dots	Trichotillomania	Clinical history + dermoscopy	Psychology referral
Red/pink dots + arborising vessels + keratotic scale	Discoid lupus (DLE)	ANA, biopsy	Urgent referral

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References

APA 7th edition format.

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2. Campos, J. G., Oliveira, C. M., Romero, S. A., & Pinto, G. M. (2020). Trichoscopic findings in primary cicatricial alopecias. Skin Appendage Disorders, 6(4), 232–238. https://doi.org/10.1159/000507960
3. Crispin, M. K., & Tcheung, W. J. (2018). Trichoscopy for the general dermatologist. Dermatologic Clinics, 36(4), 467–480. https://doi.org/10.1016/j.det.2018.05.013
4. Hughes, R., Chiaverini, C., Bahadoran, P., & Lacour, J. P. (2011). Corkscrew hair: A new dermoscopic sign for diagnosis of tinea capitis in black children. Archives of Dermatology, 147(3), 355–356. https://doi.org/10.1001/archdermatol.2011.31
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7. Miteva, M., & Tosti, A. (2013). Dermoscopy guided scalp biopsy in cicatricial alopecia. Journal of the European Academy of Dermatology and Venereology, 27(10), 1299–1303. https://doi.org/10.1111/j.1468-3083.2012.04530.x
8. Ross, E. K., Vincenzi, C., & Tosti, A. (2006). Videodermoscopy in the evaluation of hair and scalp disorders. Journal of the American Academy of Dermatology, 55(5), 799–806.
9. Rudnicka, L., Olszewska, M., Rakowska, A., Slowinska, M., & Czuwara, J. (2008). Trichoscopy: A new method for diagnosing hair loss. Journal of Drugs in Dermatology, 7(7), 651–654.
10. Rudnicka, L., Olszewska, M., & Rakowska, A. (Eds.). (2012). Atlas of trichoscopy: Dermoscopy in hair and scalp disease. Springer.
11. Slowinska, M., Rudnicka, L., Schwartz, R. A., et al. (2008). Comma hairs: A dermoscopic marker for tinea capitis. Journal of the American Academy of Dermatology, 59(5 Suppl), S77–S79.
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