Linear Alopecia Areata in a 4-year-old Patient: A Rare Clinical Variant

Alopecia areata (AA) is a common, immune-mediated, nonscarring hair loss disorder targeting the anagen hair follicle which presents with sharply demarcated patches of hair loss and can be found in any age.[1] According to the extent of hair loss, AA can be divided into three categories: Alopecia circumscripta where involvement is localized and patchy; alopecia totalis, which causes whole scalp hair loss and alopecia universalis, characterized by complete scalp and body hair involvement.[1] Variants based on morphological pattern include alopecia reticularis in which there are tiny multiple, reticulate patches; ophiasis type characterized by a continuous patch of alopecia in the occipito-temporal region and Sisaipho type or ophiasis inversus where the hair loss involves the fronto-parietal-temporal area.[1] However, linear variant of AA in band like blaschkoidal pattern is exceedingly rare.[2] Here, we report the unique case of linear variant of AA in a 4-year-old child. A 4-year-old male child presented with asymptomatic patchy hair loss to the dermatology department which started as a small patch over the temple, progressing in a band-like pattern over the right scalp for 3 months. There was no similar family history or history of itching. There were no lesions elsewhere on the body or history of any significant systemic illness. Examination revealed a 12 cm × 4 cm smooth, nonscarring alopecia patch in a linear pattern on the right temporoparietal region [Figure 1]. Overlying skin was smooth with no erythema or atrophy. There was no cervical lymphadenopathy or scaling or any nail changes. The hair pull test and KOH mount were negative. Trichoscopy displayed short upward regrowing hairs, yellow dots, and few vellus hairs, with no dystrophic hairs or scaling [Figure 2a and b]. Based on the clinical presentation, after confirming trichoscopy findings, other causes of nonscarring alopecia in children were ruled out while avoiding biopsy considering patient’s age, thus leading to the diagnosis of a rare linear variant of AA. The patient was kept under close follow-up.Figure 1: Well-defined smooth patch of alopecia in the linear pattern over the right temporoparietal regionFigure 2: (a) Multiple short upward regrowing hair (red circle) with few vellus hairs (yellow arrow) on trichoscopy (DL4, polarized mode, ×10). (b) Trichoscopy in the periphery of patch revealing multiple yellow dots (red circle) and vellus hairs (yellow arrow)AA is a complex multifactorial disease with remissions and recurrences interspersed with unpredictable prognosis in the pediatric population.[1] It has a gravely negative effect on the child’s quality of life in addition to significantly affecting the parents’ emotional well-being. Nearly half of the patients are expected to achieve spontaneous regrowth within a year of diagnosis.[1] However, there is a paucity of data on this atypical clinical variant of linear AA in a child and whether there are any possible implications on disease course or prognosis when compared to the other common variants of AA found in the pediatric population.[2] Trichoscopy is a rapid, noninvasive, and contemporary way to evaluate alopecias providing ease of diagnosis by allowing for high magnification and visualization.[3] The common trichoscopic findings of AA usually reveal exclamation hairs, black dots, coudability hairs and yellow dots, while long-standing cases show empty follicles. Short regrowing vellus hairs and pigtail hairs signifying hair regrowth and thus indicating good prognosis.[3] Differential diagnoses include tinea capitis, triangular temporal alopecia, trichotillomania, and pressure-related alopecia.[1] Alopecia in a linear form is unusual with only a small number of instances documented in the medical literature.[2,4,5] Only a single case of Blaschko linear AA in a 12-year-old child has been reported in 2022 by Albaghsi et al.[4] Two case reports of linear AA in adults exist in the medical literature till date where one was described in a 35-year-old male and the other in a 28-year-old male, respectively.[2,5] In both, the diagnosis of linear AA was confirmed with histopathological evidence to differentiate from close differentials such as linear lupus erythematosus profundus in scalp and linear morphea.[2,5] In this case, however, biopsy could not be performed considering its invasive nature and parents’ apprehension considering child’s age. After careful clinicotrichoscopic correlation and ruling out other differentials, a diagnosis of this rare linear variant of AA was made. The additional trichoscopic finding of short upward regrowing hair and absence of markers of disease activity like exclamation mark hair or black dots in this case may point toward a possible association of this atypical linear variant and good prognosis in pediatric AA. However, according to the author’s knowledge, there is a lack of evidence in the existing medical literature[2,4,5] to support this association as this is only the second case of linear AA being described in a child thus making it the youngest case of linear AA to ever be reported. In conclusion, AA can present with varying clinical patterns and trichoscopy plays a crucial role in diagnosing such rare variants with precision, especially in the pediatric population. Declaration of consent The authors certify that they have obtained all appropriate consent forms, duly signed by the parent(s)/guardian(s) of the patient. In the form, the parent(s)/guardian(s) has/have given his/her/their consent for the images and other clinical information of their child to be reported in the journal. The parents understand that the names and initials of their child/children will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.