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Segmental alopecia areata affecting the scalp, eyebrow, and lash line: A novel presentation

AA: alopecia areata INTRODUCTION Alopecia areata (AA) affects 1 to 2 percent of the population and is often associated with autoimmune conditions such as vitiligo, thyroid disease, rheumatoid arthritis, and type 1 diabetes mellitus. Reported patterns of AA include a single patch of hair loss, multiple patches of hair loss, reticular, ophiasis, sisaipho, alopecia totalis, and alopecia universalis. Alopecia presenting in a linear distribution is rare with 2 cases in the literature of linear AA of the scalp. Linear alopecia has more frequently been associated with lupus erythematosus profundus.


INTRODUCTION
Alopecia areata (AA) affects 1 to 2 percent of the population and is often associated with autoimmune conditions such as vitiligo, thyroid disease, rheumatoid arthritis, and type 1 diabetes mellitus. 1 Reported patterns of AA include a single patch of hair loss, multiple patches of hair loss, reticular, ophiasis, sisaipho, alopecia totalis, and alopecia universalis. 2 Alopecia presenting in a linear distribution is rare with 2 cases in the literature of linear AA of the scalp. 3 Linear alopecia has more frequently been associated with lupus erythematosus profundus. 3

CASE REPORT
A 24-year-old woman presented with a 3-year history of localized hair loss involving a linear streak on her right forehead, right medial eyebrow, and right medial lash line. The hair loss started on the scalp and progressed to involve the eyebrow and lash line over 6 months. She was healthy and took no regular medication. There was no associated pain or itch in the affected areas. She had no family history of AA or autoimmune disease. Examination revealed nonscarring alopecia of the right anterior scalp, right medial eyebrow, and right medial right lash line in a linear pattern (Fig 1). The skin in the affected areas appeared healthy, and no perifollicular erythema or scaling was observed. Hair pull test was negative. Dermoscopic examination revealed preserved follicular openings. Yellow dots were visible as were exclamation point hairs and broken hairs (Fig 1).
There was no evidence of vellus hairs. She had undergone tattooing of her medial eyebrow to camouflage the affected area (Fig 1). There was no hair loss elsewhere, and her nails appeared healthy. Full blood count, renal profile, liver profile, iron studies, ferritin, vitamin B12, folate, vitamin D, and thyroid function tests were normal. Connective tissue disease screen was negative. Complement levels were normal. A punch biopsy from the affected area on her scalp revealed a reduction in the number of hair follicles with a distortion in the appearance of residual follicles. Follicular plugging was seen. There was mild perifollicular chronic inflammation without interface changes (Fig 2). Histology was reported to be in keeping with AA. One ml of triamcinolone (10 mg/ml) was injected across the affected areas of the scalp and eyebrow. At 3-month review, no response was observed. A further injection of 1-ml intralesional triamcinolone 10 mg/ml across the affected area of her scalp and eyebrow did not yield a response on review 2 months later.

DISCUSSION
Characteristic dermoscopic features of hair loss in AA include yellow dots, broken hairs, exclamation mark hairs, and black dots among others. 4 In our  case, dermoscopic examination of the scalp and eyebrows revealed both of these features. Segmental vitiligo is characterized by early onset, rapid stabilization, and unilateral distribution. 5 The etiology of segmental vitiligo remains elusive. Possibilities proffered include neuronal mechanisms, somatic mosaicism, a specific migration pattern of cytotoxic T cells, or a combination of some or all of the proposed theories. 5 A similar pathomechanism may account for the segmental nature of the alopecia observed in our case. Segmental vitiligo is less responsive to treatment with topical steroids, topical calcineurin inhibitors, and phototherapy. However, there is some evidence that treatment early in the course of disease is more effective. 6 The fact that segmental vitiligo is less responsive to treatment may also indicate a similar pathomechanism as in our case, treatment has not been successful to date.
To our knowledge, this case is the first case of AA affecting the scalp, eyebrow, and lash line in such a unilateral linear distribution. This may reflect the complex pathogenesis associated with AA. It is important to consider AA as a differential diagnosis for alopecia presenting in a linear distribution.