- Aphtha is painful mucosal ulceration of the oral mucosa, more rarely also of the genital mucosa, which has a whitish fibrin coating and is surrounded by an inflamed, reddened rim.
- Types:
- Minor aphthae tend to be small (less than 1 cm in diameter) and shallow.
- Major aphthae are larger and involve deeper ulceration.
- Herpetiform aphthae frequently are more numerous and vesicular in morphology
