How are trichoscopy pictures used to diagnose and treat hair and scalp disorders?

Trichoscopy in Hair and Scalp Disorders: Diagnostic and Treatment Applications

Primary Diagnostic Role

Trichoscopy (dermoscopy of the scalp and hair) is a simple, non-invasive bedside tool that aids diagnosis of hair and scalp disorders by identifying specific patterns that distinguish between conditions, guide biopsy site selection when needed, and monitor treatment response photographically at follow-up visits. 1, 2

Key Trichoscopic Findings by Condition

Alopecia Areata

• Yellow dots are the most commonly reported feature (present in 6-100% of patients) and indicate active disease progression when regularly round in appearance 1, 3
• Exclamation mark hairs (dystrophic hairs with fractured tips) are characteristic findings that help distinguish alopecia areata from other conditions like trichotillomania 1, 3
• Black dots (cadaverized hairs fractured before emergence from scalp) appear in 0-84% of cases 1, 3
• Short vellus hairs are present in 34-100% of patients 3
• Tapered hairs (5-81% of cases) may play an important role in differential diagnosis despite being less frequently reported 3
• No single trichoscopic feature is pathognomonic; diagnosis requires the coexistence of multiple findings 3

Differential Diagnosis Features

Trichotillomania

• Broken hairs remain firmly anchored in the scalp (still in anagen phase), unlike the exclamation mark hairs of alopecia areata 1
• Hair loss pattern is incomplete rather than the well-demarcated patches seen in alopecia areata 1

Tinea Capitis

• Scalp inflammation is present, though signs may be subtle 1
• Requires fungal culture for definitive diagnosis 1

Scarring Alopecias

• Trichoscopy helps identify scarring conditions early and distinguish them from non-scarring alopecias like alopecia areata 2, 4

Clinical Applications Beyond Diagnosis

Treatment Monitoring

• Trichoscopy provides photographic documentation at each follow-up visit to objectively evaluate treatment response 2
• This is particularly valuable given that 34-50% of alopecia areata patients recover spontaneously within 1 year, making treatment efficacy assessment challenging 1

Biopsy Guidance

• When diagnosis remains uncertain after trichoscopy, the technique helps select the optimal biopsy site 2, 5
• This is especially useful in cases of diffuse alopecia areata or early scarring alopecia where clinical diagnosis is difficult 1
• Trichoscopy may obviate unnecessary biopsies when characteristic patterns are clearly identified 2

Systemic Disease Detection

• Trichoscopy can identify features associated with systemic conditions including systemic lupus erythematosus, systemic sclerosis, cutaneous lymphomas, and secondary syphilis 6
• Thick arborizing and tortuous vessels are common in connective tissue diseases 6

Algorithmic Approach to Using Trichoscopy

Step 1: Initial Clinical Assessment

• Examine for patchy versus diffuse hair loss patterns 1
• Look for scalp inflammation, scaling, or erythema that suggests tinea capitis or scarring conditions 1
• Assess for exclamation mark hairs at patch margins (visible clinically before trichoscopy) 1

Step 2: Trichoscopic Examination

• Identify presence of yellow dots (suggests alopecia areata) 1, 3
• Look for exclamation mark hairs and black dots (supports alopecia areata diagnosis) 1, 3
• Assess hair shaft characteristics: firmly anchored broken hairs suggest trichotillomania rather than alopecia areata 1
• Evaluate for vascular patterns that may indicate systemic disease 6

Step 3: Determine Need for Additional Testing

• If trichoscopy shows multiple characteristic features of alopecia areata (yellow dots + exclamation mark hairs + black dots), proceed with clinical diagnosis without further testing 1, 3
• If scalp inflammation is present, obtain fungal culture to rule out tinea capitis 1
• If diagnosis remains uncertain despite trichoscopy, proceed to skin biopsy at the site identified by trichoscopy as most representative 1, 2
• Consider serology for lupus or syphilis only when clinical features suggest these conditions 1

Step 4: Treatment Planning and Monitoring

• Use trichoscopy to establish baseline photographic documentation before initiating treatment 2
• Repeat trichoscopic examination at follow-up visits to objectively assess treatment response 2
• Remember that spontaneous remission occurs in 34-50% of alopecia areata cases within 1 year, making trichoscopic monitoring essential to distinguish treatment effect from natural history 1

Common Pitfalls to Avoid

• Do not rely on a single trichoscopic finding to diagnose alopecia areata; multiple features must coexist for accurate diagnosis 3
• Do not order excessive laboratory tests when trichoscopy clearly demonstrates characteristic patterns of alopecia areata 7
• Do not overlook trichoscopy as a non-invasive diagnostic tool that can provide valuable information before proceeding to biopsy 7
• Do not assume all patchy hair loss is alopecia areata; use trichoscopy to distinguish from trichotillomania, tinea capitis, and early scarring conditions 1
• Do not forget the psychological impact of hair loss; trichoscopic confirmation of diagnosis helps guide appropriate counseling about prognosis 1

Prognostic Value

• Disease severity at presentation (assessed clinically and trichoscopically) is the strongest predictor of long-term outcome 1
• Patients with less than 25% hair loss initially have 68% chance of being disease-free at follow-up, compared to only 8% for those with more than 50% initial hair loss 1
• Trichoscopic documentation allows objective tracking of disease extent over time 2