Recurrent episodes of ulceration of the oral mucosa, typically presenting as painful, sharply circumscribed fibrin-covered mucosal defects with a hyperemic border.
Comment:
Recurrent aphthous stomatitis can be classified into three forms, with minor ulcers (over 80% of RAS cases) being less than 1 cm in diameter and self-limiting; major ulcers being over 1 cm in diameter with potential scar formation; and herpetiform ulcers manifesting as recurrent episodes with multiple small ulcers throughout the oral mucosa.