Angular cheilitis (also referred to as perleche) manifests as an inflamed lesion on the mouth. It can also look like chapped lips. It can be caused by many things including bacteria, fungus, malnutrition, or by an intolerance to a certain type of yeast called candida albicans. This intolerance can lead to a fungal infection that is called candidiasis.
In terms of malnutrition, angular cheilitis is most often caused by a deficiency of iron, zinc, and riboflavin. While it may be a simple case of not eating the right food that is causing the malnutrition, it is sometimes something more serious referred to as celiac disease. Celiac disease is a disease in which the autoimmune system attacks itself and damages the lining of the small intestine preventing the absorption of nutrients.