Angina bullosa hemorrhagica (ABH) is an oral mucosal blood blister that develops without blood dyscrasia or vesiculobullous disorder. Although a minor mucosal trauma has been suggested as a triggering factor for ABH, its etiopathogenesis, especially the causative role of systemic conditions, is largely unknown. We investigated the presence or absence of local factors as well as systemic background disease in 16 patients with ABH arising in the soft palate. All the lesions were solitary, and 75% of them (n = 12) appeared during the ingestion of hard or crispy food. With regard to underlying systemic conditions, hypertension was the most common (n = 6), and asthma, insomnia, diabetes mellitus, rheumatoid arthritis, gastrointestinal disorder and hyperuricemia were also recorded (n = 1 each). Five patients had no significant background disease. There were no recalcitrant or recurrent cases. In conclusion, the present study has revealed that scratching of the oral mucosa during eating plays an important role in the formation of ABH. Hypertension appears to be the most frequent background condition, but its pathogenic relationship with ABH remains speculative, as hypertension is fairly common in adults.

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The number of published cases of adenomatoid odontogenic tumor (AOT) has steadily increased, and about half were reported in Asian populations. Although the clinicopathologic profile of AOT has been extensively reported, factual knowledge of its pathogenesis is rudimentary at best, and there is controversy as to precisely which odontogenic epithelium it arises from. AOT is a successional tooth-associated lesion which develops during the mixed dentition. The permanent successor differs from its deciduous predecessor in that it has an eruptive pathway from the dental follicle to the gingiva, the gubernaculum dentis. With this background in mind, the present review focuses mainly on the early development of AOT. We successfully demonstrated a close spatial relationship between AOT and the gubernaculum dentis in a typical case. From further observations of the same AOT in which an enclosed permanent canine showed enamel hypoplasia, it is possible to pinpoint areas around the crown of a developing successional tooth in continuity with the gubernaculum dentis as starting points. In addition, we discuss the unifying histogenetic concept of three clinical variants, namely, pericoronal (follicular), extracoronal (extrafollicular), (see Article note) and peripheral.