Clinically, 3 forms of recurrent aphthous ulceration exist: major, minor, and herpetiform.
Recurrent aphthous stomatitis is distinguished from aphthous-like ulceration by exclusion of underlying systemic conditions (e.g., Behcet's syndrome, HIV/AIDS, or cyclic neutropenia).
Diagnosis is based on the history and clinical examination with exclusion of a systemic aetiology; there are no specific laboratory findings.
Topical corticosteroids and anti-inflammatory agents are the mainstay of treatment. Severe or refractory cases may require systemic therapy.
Recurrent aphthous stomatitis (RAS) is a common condition of the oral mucosa that presents in patients who are otherwise healthy. It is characterised 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) may occur associated with systemic disease, including autoinflammatory syndromes (e.g., periodic fever with adenitis, pharyngitis, and aphthae [PFAPA syndrome], Behcet's syndrome, Crohn's disease), and immunodeficiency states (e.g., nutritional defects such as in coeliac 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.  
Consultant and Honorary Senior Lecturer in Oral Medicine
Glasgow Dental Hospital and School
JT declares that she has no competing interests.
We would like to gratefully acknowledge the late Professor Crispian Scully for his contribution to this topic.
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
Great Maze Pond
PS declares that she has no competing interests.
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