**Alopecia Areata**

**Alopecia Areata**

Burhan Engin, Muazzez Çiğdem Oba and Yalçın Tüzün Yalçın Tüzün Additional information is available at the end of the chapter

Burhan Engin, Muazzez Çiğdem Oba and

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/66594

#### **Abstract**

Alopecia areata is an organ-specific autoimmune disease targeting hair follicles. It causes nonscarring hair loss. The prevalence rate of the disease is approximately 1 in 1000 people worldwide. The condition is most commonly seen as circular areas of hair loss, but it may sometimes be as extensive as to involve the whole scalp or whole body. The complex pathophysiology of alopecia areata involves an autoimmune basis. Association of alopecia areata with other autoimmune diseases, such as thyroiditis and vitiligo, and the good response of patients to immunosuppressive treatment support an autoimmune etiology. Although some poor prognostic signs are defined, the course of the disease is unpredictable and the response to treatment can be variable. To date, there are neither preventive nor curative measures to deal with the condition. First-line therapy for patchy disease is topical and intralesional steroids, whereas extensive disease is conventionally managed with immunotherapy. New treatment agents, such as excimer laser, low-dose recombinant interleukin 2, Janus kinase inhibitors, and simvastatin/ezetimibe, are promising.

**Keywords:** alopecia areata, pathogenesis, autoimmunity, squaric acid dibutylester (SADBE), diphenylcyclopropenone (DPCP)

### **1. Introduction**

Alopecia areata is an organ-specific autoimmune disease targeting hair follicles. It causes nonscarring hair loss. The condition is most commonly seen as circular areas of hair loss, but may sometimes be as extensive as to involve the whole scalp or whole body [1]. Although some poor prognostic signs are defined, the course of the disease is unpredictable and the response to treatment can be variable [2]. To date, there are neither preventive nor curative measures to deal with the condition [3].

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2017 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
