Recurrent aphthous stomatitis.

Recurrent aphthous stomatitis (RAS) is the most common clinical disease of the oral mucosa. Its prevalence in the general population varies between 5 and 25%, with its peak appearance in the second decade of life. So far, the etiopathogenesis is not clear. In genetically predisposed patients, the effect of certain triggering factors would initiate the proinflammatory cytokine cascade directed against certain regions of the oral mucosa. Ulcers are round or oval with well-defined erythematous margins and a shallow ulcerated center covered with a gray or yellowish fibrinous pseudomembrane. The ulcers may reappear at intervals of a few days and months. Given the appearance of periodic thrush in the oral mucosa, the first thing to do is to make a correct differential diagnosis, rule out associated systemic diseases and assess treatable causes before reaching the diagnosis of RAS. At present, there is no curative treatment.