• Recurrent aphthous ulcers begin in the second and third decades of life and diminish in severity with age; ulcers are episodic or continuous and only on the nonkeratinized mucosa, although tongue dorsum may be involved in hematinic deficiency; a yellow fibrin membrane with surrounding erythema is present (Fig. 7-1, A-C).

• Minor ulcers are the most common, are smaller than 1 cm in size, and last 1 to 2 weeks; major ulcers are the least common, are larger than 1 cm in size, last for weeks or months, and often are associated with scarring—this form is often seen in HIV/AIDS. Herpetiform ulcers are uncommon and number more than 10 minor ulcers at each episode; severe aphthous ulcers present as continuous ulcerations.

• Traumatic ulcers can occur whenever there is history of trauma, particularly if the area is protuberant (see Fig. 7-1, D and E).

• Fibrin membrane with enmeshed neutrophils and underlying granulation tissue with acute and chronic inflammatory cells confined to the lamina propria; adjacent epithelium exhibits spongiotic pustules and reactive atypia (such as multinucleated epithelial cells and basal cell hyperplasia) (Fig. 7-2); traumatic ulcers often show adjacent hyperparakeratosis and surface bacterial colonies.

• Early or healing lesions show subepithelial fibrin deposition, spongiotic pustules, reactive epithelial atypia with multinucleated epithelial cells, and often intraepithelial hemorrhage (Fig. 7-3).

• Spread of inflammation to underlying muscle may lead to presence of eosinophils and histiocyte-like mononuclear cells (Fig. 7-4) (see Traumatic Ulcerative Granulomas later in this chapter.)

• Evaluate for herpes simplex virus in the adjacent epithelium, and cytomegalovirus and fungi in the lamina propria in immunocompromised patients.

• Neutropenic ulcers have scarce neutrophils (Fig. 7-5).

• Medication-induced oral ulcers are not strictly aphthae and are particularly dramatic in patients on mammalian target of rapamycin (mTOR) inhibitors.

• Coagulation of the epithelium suggests concomitant contact with a caustic agent.

• Topical or systemic steroid therapy or other immunosuppressive agents (see Appendix A) and topical analgesia are indicated.

• For systemic conditions presenting with aphthous-like ulcers, careful history-taking and work-up are important.

• Adenotonsillectomy may be effective in some patients with PFAPA syndrome.