Use of Trichoscopy in Identifying Common Hair Loss Disorders
Trichoscopy, the term coined to describe dermoscopic imaging or the hair and scalp, is a noninvasive technique that can be used to visualize hair and scalp structures, positioning it as a valuable supplementary tool in the diagnosis of common scarring and nonscarring hair loss disorders in all Fitzpatrick skin types. This practice can also be used in monitoring disease progression and/or improvement with treatment.
SPECIAL COVERAGE: SDPA Annual Summer Conference 2021, Chicago, July 22-25, 2021
In a virtual presentation at the SDPA Annual Summer Conference 2021, Katherine Omueti Ayoade, MD, PhD (pictured, right), from the Department of Dermatology at UT Southwestern Medical Center (UTSW), in Dallas, Texas, discussed how dermoscopy can assist clinicians with clinical diagnoses, work up, treatment, and follow up in patients presenting with hair loss disorders. Dr. Ayoade’s presentation aimed to answer important questions related to practicing trichoscopy. Here, we explore the answers to these questions gleaned from Dr. Ayoade’s presentation.
What differences can be seen in the “healthy” scalp versus the scalp of a patient presenting with a hair loss disorder?
In the healthy scalp, there are evenly spaced groups of few shafts coming out of the same follicular ostium. These groups can be classified as single, double, and at most triple hair units. You can also observe the following key features in a healthy scalp: 1) “honeycomb-like” pigment network, 2) pinpoint white inter-follicular dots, and 3) follicular units where hairs mostly emerge in groups of twos.
While it is easy to detect all three of these features using trichoscopy, differences between a “healthy” scalp and scalp showing signs of hair loss is dependent upon the individual hair loss disorder.
The highlight of this presentation was Dr. Ayaode’s comprehensive review of main dermoscopic characteristics to look for in some of the more common hair loss disorders, such as androgenetic alopecia (AGA), alopecia areata (AA), traction alopecia, central centrifugal cicatricial alopecia (CCCA), and lichen planopilaris (LPP), with real-world magnified images of each disorder that pointed out the presence of these features.
Main Characteristics of Common Hair Loss Disorders
Anrogenetic alopecia. Trichoscopy of androgenetic alopecia (AGA) is characterized by hair diameter variability greater than 20%. This measurement describing the diversity of hair shaft diameter, is termed anisotrichosis and is considered a distinguishing feature of AGA. Peripilar signs, the presence of what looks like perifollicular “halos,” and “empty” follicles are other important trichoscopic features of AGA.
Alopecia areata. There is a long list of trichoscopic features to look for in patients with alopecia areata (AA). This list is best organized by prevalence in the reported literature. According to Waśkiel et al,1 prevalence of features seen in AA have been reported from highest to lowest as follows: yellow dots, short vellus hairs, black dots, broken hairs, exclamation mark hairs, upright regrowing hairs, pigtail (circle) hairs, and Pohl-Pinkus constrictions. It’s important to note that appearances vary by skin type. In patients with Fitzpatrick skin type IV–VI, the trichoscopy feature “yellow dots” are uncommon; empty follicles look white instead of yellow when observed in this skin type.
Traction alopecia. The main dermoscopic feature of traction alopecia is the presence of cylindric white hair casts encircling several hair shafts. The presence of hair casts surrounding the hair shafts at the periphery of patch indicates on-going traction and suggests alopecia is likely to progress. The earliest clinical sign of traction on the scalp is perifollicular erythema, which may progress to folliculitis with continued traction. Severity increases through stage progression; early TA is typically non-scarring, whereas scarring occurs in late-stage TA. Scarring in TA under trichosopy presents as irregular distribution of white dots and irregular white patches.
Central centrifugal cicatricial alopecia. While AA has a long list of characteristics, the trichoscopic features of central centrifugal cicatricial alopecia (CCCA) are few. The tell-tale sign of CCCA is the appearance of peripilar white/gray halos, an area that represents a suitable skin biopsy site in this patient population. Other scarring features of CCCA include disrupted pigmented network and loss of follicular openings. CCCA has been associated with traumatic grooming practices, such as “hot combing.”
Lichen planopilaris. Lichen planopilaris. (LPP) is a rare inflammatory condition that results in patchy progressive permanent hair loss mainly on the scalp. In active disease, trichoscopy shows scalp erythema, absence of follicular openings, and thick peripilar casts surrounding most of the emerging shafts. Broken hairs with surrounding peripilar casts, tufts are other dermoscopic findings, and vellus hairs are often absent in LPP.
In conclusion, with enhanced knowledge of the dermoscopic characteristics of hair loss disorders, clinicians can add trichoscopy to help make the clinical diagnosis, guide biopsy site selection, and monitor treatment progress.
References
1. Waśkiel A, Rakowska A, Sikora M, Olszewska M, Rudnicka L. Trichoscopy of alopecia areata: An update. J Dermatol. 2018;45(6):692-700. doi:10.1111/1346-8138.14283
Byline: Angela Saba, Managing Editor, Journal of Dermatology for Physician Assistants
Pictured: Katherine Omueti Ayoade, MD, PhD, delivering a virtual presentation during the SDPA Annual Summer Conference 2021 in Chicago (July 22-25, 2021).
Posted: August 12, 2021