Blood blisters of the oral mucosa (angina bullosa haemorrhagica).

Angina bullosa haemorrhagica is a benign phenomenon that is characterized by the sudden appearance of a blood blister on the oral mucosa in the absence of an identifiable cause or systemic disorder; local trauma has been suggested to be the most likely contributory factor. No treatment is required. Angina bullosa haemorrhagica affects mainly middle-aged and elderly people. There is no strong predilection for either men or women. In this article nine patients with such blisters are described. Blood blisters apparently are more common than has been suggested in the literature.