Esophagitis, or oesophagitis is a phenomena of inflammation in esophagus. Acute esophagitis can be catarrhal or phlegmonous but chronic esophagitis may be hypertrophic so atrophic causing disturbance in diagnostic. Source is generally: Candida (Esophageal candidiasis) for fungus and Herpes simplex or Cytomegalovirus for viral source.
Thermography can be used to diagnose it or endoscopy:
Infrared thermal imagery of esophagitis; source:Pr José Travassos Valdez