Image taken from Clinical Guide to Oral Diseases.
Angina bullosa hemorrhagica (ABH) is an acute， benign condition characterized by the development of subepithelial bullae filled with blood that are not attributed to any systemic disorders. A chronic trauma, consumption of hot and spicy or abrasive foods, or difficulties in restorative or periodontal treatment are considered to be the commonest causes.
Chronic use of steroids, especially inhalers, causes oral mucosa atrophy and decreases the submucosa’s elastic fiber content, resulting in capillary. Diabetes mellitus has also been associated with hemorrhagic bulla formation due to increased vascular fragility in these patients, and not to the drug for blood sugar reduction. Similar bullae could also be seen in patients who take antibiotics or bronchodilators and have various autoimmune diseases. As for NSAIDs, these drugs are responsible for peptic ulcers and bleeding from the intestine, but more rarely for skin bullous rash and fever.
The inflammatory response in ABH is intense and located only at the superficial parts of submucosa, often containing neutrophils but not eosinophils and mast cells.