**2. Prevalence**

Lymphocytic esophagitis is a very rare condition. In 2012, Haque *et al*. estimated its prevalence to 0.1% in the United States [2]. In their cohort that included 129,252 esophageal biopsies, a diagnosis of lymphocytic esophagitis was made in only 119 patients. Since Rubio's first publication, there is a marked increase of its incidence, probably because of pathologists' and gastroenterologists' awareness [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.

Moreover, since it is a novel entity and most of the studies are from North America, worldwide prevalence has not been evaluated.
