Trichoscopy-assisted hair pull test: A helpful adjunct to trichoscopy for diagnosing and managing alopecias.

Dear Editor,

Non‐invasive techniques constitute valuable tools in the diagnostic work‐up of patients with hair loss. Amongst them, hair pull test and trichoscopy are well‐established. , , A classic trichogram, as a semi‐invasive method, enables visualisation of proximal hair shafts and hair bulbs, which is impossible with trichoscopy. Invasiveness, need of special equipment and time requirements make this method, however, not generally applicable.

To diminish the gap between non‐invasive trichoscopy and microscopic assessment of entire hairs under the light microscope, we propose to perform a ‘trichoscopy‐assisted hair pull test’ in patients whose pull test is positive. The addition of dermoscopy enables immediate assessment of proximal hair shafts/hair roots of pulled hairs with magnification.

The following three cases of female patients with predominant hair thinning of the crown area – a clinical pattern suggestive of androgenetic alopecia (AGA) – will demonstrate diagnostic benefit and therapeutic impact of this method in daily routine.

Case 1

A 22‐year‐old female patient reported rapid‐onset hair shedding. Patient history and laboratory results were otherwise unremarkable. On clinical examination, there were distinct thinning of the crown area (Fig. 1a) and a positive hair pull test all over the scalp. Trichoscopy showed multiple regrowing hairs beside single hair units, reflecting concomitant hair loss and hair regrowth, as observed in telogen effluvium (TE). Surprisingly, dermoscopy of pulled hairs revealed a pencil point‐like appearance of proximal hair portions (Fig. 2a), a characteristic light microscopy finding in alopecia areata (AA). A subsequent dermoscopic examination of eyebrows actually revealed dystrophic hair shafts in‐vivo (Fig. 1a). A thorough re‐evaluation of scalp hairs showed subtle bending of several hairs at scalp level due to incipient thinning of proximal hair shafts (‘coudability hairs’; Fig. 1a), an early trichoscopic finding in AA. In the following, the patient developed alopecia areata universalis with satisfactory response to steroid pulse therapy.

Figure 1

Clinical and trichoscopic images of cases 1–3. (a) Case 1 ‐ diffuse AA. Thinning of the crown area seen on clinical examination (upper left inset). Dermoscopy shows predominance of single hairs emerging from individual follicular ostia (single hair units), subtle bending of several hairs at scalp level (arrows), short bundled regrowing hairs (black arrowheads) and few Pohl‐Pinkus constrictions (white arrowhead). The eyebrows display dystrophic hair shafts, such as broken hairs and ‘exclamation mark’‐hairs (arrow; upper right inset). (b) Case 2 ‐ methotrexate‐induced acute TE with AGA. Diffuse thinning of the crown area is seen (upper left inset). Trichoscopy of the frontal scalp shows distinct variability of hair shaft diameter (arrows), predominance of single hairs emerging from individual follicular ostia and presence of multiple short vellus hairs (arrowhead). Trichoscopy of occipital scalp reveals age‐appropriate hair and scalp findings (upper right inset). (c) Case 3 – LPP. Diffuse thinning of the crown area with small alopecic patches is seen (upper left inset). Trichoscopy without immersion medium displays reduced hair density, erythema and concentrically arranged layers of scales around remaining hair follicle openings/proximal hair shafts (‘peripilar casts’; arrows), and pink‐white scalp areas with focal absence of follicular openings (dashed circle). Trichoscopy with immersion medium from the same area accentuates perifollicular erythema below the (consecutively translucent) scales (arrows; upper right inset).

Figure 2

Dermoscopic pictures of hairs pulled out in cases 1–3. (a) Case 1‐ Hair shaft with thinning towards the proximal end (arrows) and dystrophic hair bulb (‘pencil point‐like appearance’; arrowhead) in case 1. (b) Case 2 shows telogen hairs with non‐pigmented, small, stiff, club‐shaped hair bulbs without inner root sheaths (arrowheads). (c) Case 3 ‐ Anagen hairs with translucent hair root sheaths around proximal hair shafts and smooth, darkly pigmented hair bulbs positioned at an acute angle to the shaft are seen (arrows).

Case 2

A 78‐year‐old female patient presented with a two‐month history of increased hair shedding. The medical history included arterial hypertension and rheumatoid arthritis, for which methotrexate was initiated three months before her visit. Her blood tests were inconspicuous. Clinical examination revealed reduced hair density, predominantly of the crown area (Fig. 1b), and a positive hair pull test in all scalp areas. Trichoscopy showed features of AGA in the crown area (i.e. hair diameter diversity, single hair units and increased proportion of short vellus hairs) and increase of single hair units in less androgen‐dependent scalp areas. Dermoscopy of pulled hairs showed telogen roots (Fig. 2b), and we suspected methotrexate‐induced acute TE in pre‐existing AGA. Indeed, hair shedding improved significantly within four months after switching her disease‐modifying anti‐rheumatic drug.

Case 3

A 65‐year‐old female patient noticed slowly progressive hair thinning for one year. The patient’s medical history was unremarkable. Clinical examination revealed thinning of the crown area with small alopecic patches, widening of the central part line, recession of the frontal hairline and decrease of eyebrows (Fig. 1c). The hair pull test was positive in clinically affected areas. Trichoscopy showed pink‐white scalp areas lacking follicular openings, erythema and scaling around remaining hair follicle openings/proximal hair shafts, and hair tufting. Dermoscopy of pulled hairs revealed anagen roots (Fig. 2c), which is indicative for a progressive scarring process. Punch biopsies confirmed the clinically suspected diagnosis of lichen planopilaris (LPP).

The conventional hair pull test is a basic diagnostic method to confirm and quantify hair loss in different scalp regions. Dermoscopic examination of pulled hairs with the same device used for trichoscopy can provide key pathophysiological information. The identification of dystrophic hair roots can help differentiate diffuse AA from other common hair loss diseases, such as shown in Case 1 (Fig. 1). In a study of Quercetai et al., the presence of dystrophic hairs was found to be the only clue for early detection of AA incognita in many patients with profuse hair shedding, clinically diagnosed as having TE or AGA. Dermoscopy of hairs extracted from frontal and occipital scalp areas in Case 2 displayed regular telogen roots, substantiating the clinically suspected diagnosis of acute TE related to methotrexate intake in association with long‐standing AGA. The hair pull test displaying anagen roots in Case 3 served as confirmatory diagnostic tool, facilitated selection of appropriate biopsy site, and – most important in scarring alopecias – enabled non‐invasive monitoring of response to systemic therapy during follow‐up. ,

We conclude that a ‘trichoscopy‐assisted hair pull test’ is a helpful non‐invasive diagnostic adjunct in the evaluation of patients with hair loss and positive hair pull test.

Patient consent for publication statement

All patients in this manuscript gave written informed consent to the publication of their clinical and dermoscopic photographs.