Linear Alopecia Areata.

Alopecia areata (AA) over scalp is known to present in various shapes and extents of hair loss. Typically it presents as circumscribed patches of alopecia with underlying skin remaining normal. We describe a rare variant of AA presenting in linear band-like form. Only four cases of linear alopecia have been reported in medical literature till today, all four being diagnosed as lupus erythematosus profundus.

INTRODUCTION

Alopecia areata (AA) is a common, usually, nonscarring type of hair loss affecting 0.1–0.2% of the general population.[1] Typically, it presents as circumscribed patches of alopecia; the skin of the affected area remain normal and smooth. Here, we report an unusual case of AA showing a linear band-like form of alopecia traversing over the center of the scalp.

CASE REPORT

A 35-year-old male patient presented with a linear bald patch on the scalp which was persisting for the past 3 years. Hair loss was initially noted in the vertex area of the scalp which then gradually progressed in a linear pattern toward the temporal region on either side in the period of 2 weeks. There was no associated itching or swelling in the alopecic area. At around 2 cm in front of the helix of pinna, a linear patch of alopecia measuring 22 cm long and 2 cm wide was seen, traversing the center of the scalp [Figure 1]. The underlying skin was smooth and normal in color without any evidence of scaling, atrophy, or induration. Nails were normal. The hair pull test and the perilesional trichogram did not yield any abnormalities. A trichoscopic evaluation revealed short vellus hair in center and hairs with the tapering base at the periphery. Histopathological examination revealed lymphocytic infiltrate in peribulbar area [Figure 2a] with an increase in telogen hair units along with the formation of a fibrous stellae [Figure 2b]. Special staining with alcian blue showed negative staining for mucin. A diagnosis of AA was considered and he was treated with monthly intralesional triamcinolone acetonide (5 mg/ml) injections along with topical minoxidil 5% solution.

Figure 1

(a and b) Linear band of alopecia traversing center of scalp

Figure 2

Histopathology (H and E, ×100) (a) peribulbar lymphoid infiltrate (b) follicular stellae and telogen unit hairs

DISCUSSION

AA over scalp is known to present in various shapes and extents of hair loss. AA has been classified into different types based on the pattern (e.g., alopecia reticularis, ophiasis, and sisiapho type) and extent of alopecia (e.g., AA circumscripta, AA totalis, and AA universalis). However, AA presenting in linear band-like form traversing center of the scalp is very rare. Four cases of histologically proven, lupus erythematosus profundus (LEP) presenting with linear alopecias have been reported in medical literature.[234] Three of these cases simulated AA clinically only to be proven otherwise by histopathology. Histopathologically, a peribulbar lymphocytic infiltrate, a so-called “swarm of bees,” is considered as the diagnostic histopathologic feature of AA in early active stage and it may be subtle or even absent in the chronic stage of AA. Increased hairs in the catagen or telogen phase, follicular miniaturization, and pigmentary incontinence around the hair follicles are also frequently found in AA, and the former two findings are more significant in long-standing lesions of AA.[5] LEP demonstrates lobular lymphohistiocytic infiltrate often with plasma cells in adipose tissue. In well-established lesions hyalinization of adipose lobules with stromal mucin deposition is prominent.[6] In the present case, scant peribulbar infiltrate, increase in catagen hair and pigmentary incontinence around hair follicle are consistent with features of a long-standing case of AA and absence of mucin deposition along with normal adipose tissue rules out LEP. In terms of linear lesions in dermatology, quite a few dermatoses can occur over the scalp such as linear scleroderma, linear lichen planus, linear psoriasis, and linear epidermal nevus.[7] All of these dermatoses show visible cutaneous changes and often they may extend to the adjoining smooth skin over the hairlines or they may involve other parts of the body simultaneously. It is difficult to explain the reason why AA occurred in a linear pattern here. AA is known for its unpredictability, and this is probably the first report in the medical literature describing the linear band-like form of AA.

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Conflicts of interest

There are no conflicts of interest.