A common condition of the oral mucosa, characterized by multiple recurrent small, erythematous, round or ovoid ulcers with circumscribed margins, typically presenting first in childhood or adolescence, often with a positive family history, and with a natural history of cessation in adult life.
Clinically, 3 forms of recurrent aphthous ulceration exist: major, minor, or herpetiform.
Recurrent aphthous stomatitis (RAS) is distinguished from aphthous-like ulceration by exclusion of underlying systemic conditions (e.g., Behcet syndrome, HIV/AIDS, or cyclic neutropenia).
Diagnosis is based on the history and clinical examination with exclusion of a systemic etiology; there are no specific laboratory findings.
Topical corticosteroids and anti-inflammatory agents are the mainstay of treatment. Severe or refractory cases may require systemic immunomodulatory therapy.
Recurrent aphthous stomatitis (RAS) is a common condition of the oral mucosa, characterized by multiple, erythematous, recurrent, small, round or ovoid ulcers with circumscribed margins, typically presenting first in childhood or adolescence.   Similar presentations of recurrent oral ulceration (aphthous-like ulceration [ALU]) may occur associated with systemic disease, including autoimmune disease (e.g., pemphigus), autoinflammatory syndromes (e.g., periodic fever with adenitis, pharyngitis, and aphthae [PFAPA syndrome], Behcet syndrome, Crohn disease), and immunodeficiency states (e.g., nutritional defects such as in celiac disease and other gastrointestinal disorders, immune defects such as HIV/AIDS, or neutrophil defects such as cyclic neutropenia); therefore, to avoid confusion, the term RAS should be reserved for ulceration seen in the absence of systemic disease.  
We would like to gratefully acknowledge the late Dr Crispian Scully for his contribution to this monograph.
Consultant for Oral Pathology and Oral Medicine
The Milton J. Dance Head and Neck Center
Greater Baltimore Medical Center
JJS declares that he has no competing interests.
Consultant in Oral Medicine
Glasgow Dental Hospital and School
DF declares that he has no competing interests.
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