A. Idiopathic

1. Aphthae - history of recurrent round or oval mouth ulcers since childhood
2. Periodic Fever, Aphthae, Pharyngitis, Adenitis
   1. History of recurrent mouth ulcers since childhood
   2. Recurrent fever, pharyngitis, lymphadenitis
   3. Clinical presentation, exclusion of other systemic disesases
3. Tumor Necrosis Factor Receptor Associated Periodic Syndrome

B. Infections

1. Recurrent herpesvirus infection
2. Cytomegalovirus (CMV) infection in immunosuppressed persons
3. HIV Infection

C. Rheumatic Diseases

1. Behcet's Syndrome
2. Reactive Arthritis (Reiter's Syndrome)
3. Sweet's Syndrome
   1. Red plaques on skin with fever
   2. Aphthous-like ulcers on genital or other mucosae
   3. Often associated with inflammatory bowel disease (IBD), leukemia
   4. May occur with high doses of colony stimulating factors (CSFs)

D. Gastrointestinal

1. Gluten-sensitive enteropathy (Celiac Disease)
2. IBD: ulcerative colitis, Crohn's Disease

E. Drugs

1. NSAIDs
2. ß-adrenergic blockers
3. Nicorandil (Ikorel®)
4. Alendronate (Fosamax®)

F. Other

1. Erythema Multiforme
2. Cyclic Neutropenia

References

1. Scully C. 2006. NEJM. 355(2):165