A vesicular and bullous eruption having a tendency to recur in summer during childhood and commonly appearing on sun-exposed skin. The lesions are surrounded by an erythematous zone and resemble a vaccination. (From Dorland, 27th ed)

A loss of mucous substance of the mouth showing local excavation of the surface, resulting from the sloughing of inflammatory necrotic tissue. It is the result of a variety of causes, e.g., denture irritation, aphthous stomatitis (STOMATITIS, APHTHOUS); NOMA; necrotizing gingivitis (GINGIVITIS, NECROTIZING ULCERATIVE); TOOTHBRUSHING; and various irritants. (From Jablonski, Dictionary of Dentistry, 1992, p842)