Alopecia areata management
Alopecia areata diagnosis
Watch Lynn Wilks describe the emotional impact on her of receiving a diagnosis of alopecia areata.
Dr Brett King, MD, PhD, of Yale School of Medicine provides an informative overview of alopecia areata diagnostics, highlighting important differential diagnoses that should be considered, as well as some of the challenges unique to the diagnosis of alopecia areata.
Clinical features of alopecia areata
Scalp hair loss in alopecia areata (AA) is most commonly patchy and well-demarcated, with complete loss of all terminal hairs in at least one area. The disorder is clinically classified according to the skin areas involved, the pattern, and the extent of hair loss (Table 1)1.
Table 1. Clinical variants of alopecia areata with their characteristic manifestations (Adapted1).
| Clinical variants of alopecia areata | Presentation |
| Patchy alopecia areata | Single or multiple circumscribed, well-demarcated patches of hair loss on the scalp |
| Alopecia totalis | Complete scalp hair loss |
| Alopecia universalis | Complete loss of facial, body and scalp hair |
| Ophiasis alopecia areata | Hair loss on the occipital and temporal scalp site |
| Inverse-ophiasis (or sisaipho) alopecia areata | Central hair loss, lateral and posterior scalp sites are spared |
| Diffuse alopecia areata/Alopecia areata incognita | Diffuse hair loss and reduction of hair density |
| Alopecia barbae | Discrete circular or patchy hair loss areas in the mustache or beard, often along the jawline, rarely diffuse thinning |
| Alopecia areata of the nails | Nail pitting, trachyonychia, red lunula, longitudinal ridging, onychomadesis, onycholysis and onychorrhexis |
A gentle hair pull test at the periphery of the patch demonstrates easily pluckable hairs. Finding multiple hairs on at least five pulls suggests active progressive hair loss.
Microscopy in the acute phase may show dystrophic anagen hair roots pulled off easily with damaged proximal ends. Supportive clinical features include patchy body hair loss, eyebrow and eyelash hair loss, and fine pitting of nails ("sandpaper nails")1.
Alopecia areata is commonly a clinical diagnosis, but trichoscopy and histopathology are valuable clinical tools to improve diagnostic accuracy
Differential diagnosis of alopecia areata
To make an effective management plan for AA, other hair loss disorders such as tinea capitis, trichotillomania, aplasia cutis, triangular alopecia, telogen effluvium and primary scarring alopecia need to be differentiated from AA (Table 2)1.
Table 2. Differential diagnoses of patchy and diffuse alopecia areata (Adapted1).
| DD Patchy alopecia areata | DD Diffuse alopecia areata | |
| Children/adolescents | Tinea capitis | Loose anagen hair syndrome |
| Trichotillomania | Telogen effluvium | |
| Temporal triangular alopecia (N. Breuer) | Congenital hypotrichosis | |
| Adolescents/adults | Mucinosis follicularis | Telogen effluvium |
| Alopecia syphilitica | Female pattern hair loss | |
| Scarring alopecia, such as CDLE, lichen planopilaris | Drug induced alopecia (antiproliferative, etc.) |
DD, differential diagnosis; CDLE, chronic discoid lupus erythematosus.
Trichoscopy of alopecia areata
Dermoscopy is a simple and safe procedure that may contribute to diagnosing AA2.
Trichoscopic features of AA are yellow dots and black dots (Figure 1A), broken hairs, "exclamation mark" hairs (tapered hairs) (Figure 1B), colour transition sign (black distal end advancing to white proximal end), and short vellus hairs (Figure 1C)2,3.
Figure 1. Trichoscopic findings in alopecia areata. All photos used with permission by DermNet (https://dermnetnz.org/image-library). Attribution-non-commercial-noderivs 3.0 New Zealand (CC BY-NC-ND 3.0 NZ). (A) Yellow dots (yellow circles) are highly sensitive, but not a specific marker for alopecia areata, as they are associated with other hair loss conditions, such as androgenetic alopecia. Black dots, also shown, observable during alopecia areata, are pigmented hairs broken, or destroyed at scalp level. (B) Exclamation mark hairs have a thin, hypopigmented proximal end, and a thicker distal end, observable during the acute progressive phase of alopecia areata. (C) Short vellus hairs are thin hairs that mark active disease, or initial response to therapy for alopecia areata.
Detecting a combination of yellow dots and short vellus hairs enhances the sensitivity of an alopecia areata diagnosis. Black dots, exclamation mark hairs and broken hairs are other common findings associated with disease activity. Rarely reported features include upright regrowing hairs and pigtail (circle) hairs2,3.
Several trichoscopy findings, rather than a single feature, are used to establish the diagnosis of alopecia areata. Short vellus hairs are observable in the initial stages of hair regrowth after treatment. AA subtypes are not associated with any specific trichoscopy findings1,3.
Histopathology of alopecia areata
Histopathological examination can support a diagnosis of alopecia areata and help stage disease severity (Figure 2).
Figure 2. Histopathologic features of intense perifollicular fibrosis in a female who had circumscribed patches of alopecia areata for two months (Adapted4). Figure reused under Creative Commons Attribution 4.0 International (CC-BY-NC-ND 4.0).
Non-sclerosing fibrous tracts in alopecia areata
Non-sclerosing fibrous tracts (residues of collapsed fibrous hair root sheaths) are observable during all stages of alopecia areata.
Peribulbar lymphocytic infiltrate
Another distinguishing feature of AA is a peribulbar lymphocytic infiltrate, called a “swarm of bees”. Staging features are telogen hairs alone, a combination of telogen and dystrophic anagen hairs and the extent of perifollicular cell infiltration and catagen conversion.
Trichotillomania
Trichotillomania is a condition with forced hair plucking that may show as follicular micro-haemorrhages. Telogen effluvium is a condition of diffuse hair loss that presents similarly to alopecia areata incognita (AAI); colour transition with proximal whitening observed in AAI helps differentiate them1,5.
Tools for assessing alopecia areata
Clinicians use the Severity of Alopecia Areata Tool (SALT) score to assess the severity of hair loss in four quadrants (left, right, front, and back) and response to treatment (Figure 3A). A baseline SALT score of >25% is considered severe AA. After treatment, a 50–90% improvement in SALT score indicates success. Modified SALT-II is a refined score that divides the scalp into 1% areas (Figure 3B). SALT I and SALT II scores rely on visual assessment without documenting specific areas of hair loss5.
(A)
(B)
Figure 3. SALT I and SALT II assessment measures for alopecia areata (Adapted5). (A) The Severity of Alopecia Areata Tool (SALT) score is calculated in quadrants across four scalp areas, then summed to generate the SALT score. (B) Modified SALT II Visual Aid and computation of ALODEX score density for each 1% of scalp area. Density is scaled from 0–10 according to the percentage of terminal hair loss (100% hair loss = 10; 90% = 9; 80% = 8; and no hair loss = 0). The density assignments in each of the 1% scalp areas in a quadrant are added; the total is divided by the maximum grade of hair loss for the percent hair loss for that quadrant. The sum of each quadrant’s score is the ALODEX score.
Other than SALT scores, the following metrics can be used for assessing alopecia areata5:
- The Alopecia Areata Progression Index (AAPI) can be calculated with the hair pull test and trichoscopy
- Patient assessment of the extent of hair loss and quality of life assessments
- Photography can be used by patients with severe AA subtypes to self-assess treatments
Prognosis of alopecia areata
The following clinical features are predictors for AA progressing to alopecia totalis (AT) or alopecia universalis (AU)5,6:
- Onset before puberty
- Chronic lesions lasting >1 year
- Family members with a diagnosis of AA
- Associated atopy (atopic dermatitis, asthma, hay fever/allergic rhinitis)
- Associated autoimmune diseases (thyroid disease, vitiligo, rheumatoid arthritis, type 1 diabetes)
- Associated depression or obesity
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