Diseases of the mucous membranes include those involving the lips, tongue, palate, gingiva, teeth, and the floor of the mouth. Inspection of this entire surface should be included in the full skin examination to screen for evidence of mucocutaneous conditions, such as lichen planus, and primary diseases of the mucosa, such as squamous cell carcinoma of the lip. Routine examination of these surfaces also allows one to become familiar with the spectrum of benign findings such as many forms of oral melanosis.
Primary conditions of the mucosal surfaces include changes to the tongue, such as median rhomboid glossitis or inflammation of the taste buds known as papillitis . Aphthous ulcers provide another example of a primary oral disease, and they are featured here with their classic round, shallow, white ulcers with surrounding bright red rims.
Many oral findings can be found in the setting of a systemic disease such as inflammatory bowel disease (IBD). In IBD there are several related mucosal diseases, including the cobblestoned appearance of the mucosa, oral ulcers, granulomatous cheilitis, and pyostomatitis vegetans. Nutritional deficiencies, fixed drug eruptions, and Behçet syndrome are examples of other systemic diseases with important mucosal findings.