Cryotherapy Versus Steroids In Alopecia Areata:Trichoscopic Evaluation

Overview

Alopecia areata is the most frequent cause of inflammation-induced hair loss with prevalence from 0.1 to 0.2%. It has no age nor sex predilection . Clinically, alopecia areata presents as a well-circumscribed patch of sudden hair loss. It affects any hair bearing area. The most common affected site is the scalp. Based on site and extent, AA can be classified into; diffuse, multi-locularis, mono-locularis, totalis, universalis, and ophiasis.

Histologically, lesional biopsies of alopecia areata demonstrate a peri\_follicullare and intra\_folliculare mononuclear cell infiltrate around anagen phase hair follicles .The infiltrate consists mostly of activated lymphocytes in particular CD4 cells as well as dendritic cells and macrophages. Many theories were implicated in pathogenesis of alopecia areata such as; autoimmune lymphocytic attack of the hair, genetic basis and environmental factors. So the pathogenesis of alopecia areata remains to be determined. Currently a widely accepted theory is the autoimmune etiology. Specific T\_cell lymphocytes, autoantibodies against anagen follicles, and various cytokines such as interferon-γ, interleukins, and tumor necrosis factor-α have been found to play a major role in alopecia areata. In addition, the immune privilege theory has been recently introduced and suggested to play a role in the pathogenesis. Many kinds of treatment modalities are present in localized alopecia areata. Injectable forms of corticosteroids are first line of alopecia areata therapy, and also topical use of steroids is widely used. Others are topical sensitization with anthrain, minoxidil and cryotherapy. In extention form of alopecia areata, systemic treatments like corticosteroids, cyclosporine and methotrexate can be used. Intralesional Corticosteroid injection: National Guidelines from British Association of Dermatologists, recommend intralesional corticosteroid therapy as the first line treatment for localized patchy alopecia areata, with approximate success rates of 60-75%. Their use was first described in 1958, with the use of hydrocortisone. Immunosuppression is the main mechanism of action. Corticosteroids suppress the T-cell-mediated immune attack on the hair follicle. Steroids with low solubility are preferred for their slow absorption from the injection site, promoting maximum local action with minimal systemic effect. The efficacy of intralesional corticosteroid injection is variable depending on the patient population treated. Cryotherapy: Cryotherapy may act through either singly or by a combination of the following mechanisms resulting in hair regrowth in alopecia areata. After initial vasoconstriction with cryotherapy, there is a significant local vasodilatation during the thaw period as the temperature reaches zero degree Celsius. Thus, cryotherapy is speculated to dilate the vessels around the affected hair follicles, with an increase in the blood flow leading to follicular hair regrowth. Moreover, local edema and inflammation occurring after cryotherapy may play a role in inducing vasodilation. Cryotherapy is also speculated to inflict partial damage to keratinocytes, especially the antigenic components of the hair follicle keratin16 and trichohyalin, which are targeted by antibodies and thus, further decrease in damaging perifollicular infiltrate. Cryotherapy may also alter tissue Langerhans cells, which in turn could alter the process of antigen presentation with further decrease in T cell infiltration. As it is known, the white hairs are spared in alopecia areata; it is hypothesized that melanocytes may have a role in the pathogenesis ofalopecia areata. Hence, cryotherapy may also act by destructing the melanocytes further preventing their role in the initiation of alopecia areata. Dermoscopy: Dermoscopy is now considered as a valuable tool in diagnosis of variable skin lesions. It is a non-invasive procedure which was initially used to assess pigmented lesions. Scalp dermoscopy (Trichoscopy) does not only facilitate diagnosis of hair disorders but also give clues about disease stage and progression. Trichoscopy allows the superimposition of the skin layers with the possibility to observe any surface or deep skin layers. The most common trichoscopic features of alopecia areata are yellow dots, micro-exclamation mark hairs, tapered hairs, black dots, broken hairs, and regrowing upright or regrowing coiled hairs. Black dots as remnants of exclamation mark hairs or broken hairs provide a sensitive marker for disease activity as well as severity of alopecia areata. Yellow dots, are considered to be the most sensitive dermoscopic feature of alopecia areata. Tapering hair is considered as a marker of disease activity and known to reflect exacerbation of disease. Trichoscopic characteristics have a clinical significance in alopecia areata for diagnosis and prognosis. Severity of alopecia tool Score: National Alopecia Areata Foundation working committee has devised "Severity of Alopecia Tool score. Severity of alopecia tool score is useful to find out the quantitative assessment of scalp hair loss.

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