A 7‐Year‐Old Male With a Linear Band‐Like Hair Patch

A previously healthy 7-year-old boy presented with a 4-month history of a linear pattern of hair loss on the scalp. There was no family history of alopecia, and he had no history of hair pulling, trauma, or application of topical medications. The affected area was 13 cm long from the crown of the head to the right frontal implant line region and 2 cm wide (Figure 1). The affected area had no scale, induration, atrophy, or erythema. Eyelashes and brows were normal. The hair pull test was positive. Dermatoscopy revealed black dots, exclamation hairs, and some pig tail hairs (Figure 2). Laboratory results revealed a normal complete blood count, thyroid function, and antinuclear antibody. A punch biopsy from the scalp was taken (Figure 3). Histopathologic findings show a lymphocytic infiltrate in the peribulbar area with an increase in telogen hair units. Hair follicles are thin and short, with bulbs extending to the mid-dermis (Figure 3; H&E, 40×). An inflammatory infiltrate causes distortion of the hair follicle architecture, resembling a “swarm of bees” pattern, without causing destruction of the follicle. Follicular stelae containing melanin are observed, and the dermis shows a focal, moderate, superficial, perivascular and lymphocytic infiltrate (Figure 3; H&E, 40×). Linear alopecia areata (LAA) is a rare form of presentation of alopecia areata (AA), with a linear pattern that differs by following a continuous, narrow tract [1]. Very few reports are published in the literature. A review published in 2023 showed 7 cases of LAA, in which 4 were children aged between 5 and 12 years [1]. Reported treatments included topical high-potency corticosteroids, systemic corticosteroid pulses, and topical minoxidil. Three of these pediatric patients showed complete regrowth, while one case had no response reported [1]. Other conditions to consider when encountering LAA include trichotillomania, congenital triangular alopecia, linear morphea, and linear variants of lichen planus and lupus erythematosus [1]. Trichotillomania is a self-induced hair loss disorder with irregular patches of hairs at varying lengths and a history of hair pulling. Dermoscopy shows broken, flame, and tulip hairs, and the “V-sign,” usually without exclamation mark hairs. Histopathology reveals follicular trauma, perifollicular hemorrhage, hair shaft remnants, and minimal inflammation [2]. Congenital triangular alopecia is a benign, non-scarring hair loss disorder, that often presents as a stable, non-progressive frontotemporal hair loss patch from infancy. Dermoscopy shows mainly vellus hairs, and histopathology reveals miniaturized follicles without inflammation or fibrosis [3]. Regarding linear morphea, particularly “en coup de sabre,” it can cause hair loss due to scalp sclerosis, leading to skin thickening in a linear pattern [4]. Dermoscopy shows reduced follicular openings, telangiectasias, and whitish areas. Histopathology reveals collagen sclerosis, adnexal atrophy, follicular dropout, lymphocytic infiltrate, and deep dermal mucin [4]. Linear cutaneous lupus erythematosus is a rare form of alopecia following Blaschko's lines [5]. Many skin conditions have been reported to manifest in linear arrangements following Blaschko's lines such as linear morphea, linear psoriasis, lichen striatus, among others [5]. In our case, we present a patient with linear cutaneous AA following Blaschko's lines on the scalp. Making a correct diagnosis is of great importance due to the impact on psychosocial, treatment, and prognostic aspects [3]. Considering the differential diagnoses, skin biopsy is the gold standard; however, its performance in the pediatric population can be challenging. Some studies offer reflectance confocal microscopy (RCM) combined with dermatoscopy as an intermediate evaluation alternative to biopsy, showing a normal honeycomb pattern and smaller, less dense follicular openings [6]. Dermoscopy findings may include yellow dots, black dots, broken hairs, short vellus hairs, exclamation hairs, and pigtail hairs, as well as a decrease in hair density [6]. Regarding histopathologic findings, in acute and subacute stages, peribulbar infiltration of lymphocytes will be present around the anagen follicles as well as a rise in the quantity of follicles in the catagen and telogen phases [7]. Treatment of LAA follows the standard approach used in AA. High-potency topical corticosteroids, such as clobetasol propionate 0.05%, are preferred over low-potency agents due to their superior efficacy in promoting hair regrowth and their favorable safety profile. Intralesional and systemic corticosteroids may also be considered as first-line options [1, 8, 9]. Topical minoxidil, used as an adjuvant therapy alongside corticosteroids, has shown acceptable results, especially in young patients [8, 10]. Various regimens of topical minoxidil have been described, including 1%, 2%, or 3% solutions or foams applied once or twice daily to the affected areas [10]. Oral minoxidil has been used in the pediatric population, but side effects are a particular concern. While topical minoxidil is typically preferred due to safety, oral minoxidil might be considered for specific situations such as hair shaft disorders, chemotherapy-induced alopecia (CIA), severe androgenetic alopecia (AGA), or extensive AA [10]. Our patient was treated with a lotion containing 5% minoxidil, 0.015% retinoic acid, and 0.05% clobetasol. The treatment was applied to the affected area once every 3 days for 3 weeks, followed by once every 4 days for 2 months. The patient demonstrated full recovery during follow-up at 2 months with dermoscopy showing signs of follicular regrowth, allowing for a gradual reduction in treatment. One year later, complete regrowth of the previously described area was observed (Figure 4). The authors declare no conflicts of interest.