Illustration of the various pathologies of the mouth other than dental. -Herpes simplex. or cold sore. -Fungal infections. fungi such as Candida : angular cheilitis. at the corners of the mouth. skin lesion with white crust and fissure. and oral candidiasis. a white deposit at the back of the mouth -Ulcer. ulceration (then necrosis) of the buccal mucosa.