II. Causes: Common
- Aphthous Ulcer
- 
                          Primary Herpetic Gingivostomatitis
                          - External Vesicles are only seen with HSV (not with Herpangina or Hand Foot and Mouth Disease)
- When herpes involves the Oral Mucosa, it typically results in lesions on the Hard Palate
 
- 
                          Herpangina
                          - Vesicles in posterior pharynx, sparing anterior pharynx
 
- 
                          Hand Foot and Mouth Disease
                          - Vesicles in anterior pharynx, sparing posterior pharynx
 
- Mouth Chemical Burn Causes
III. Causes: Rheumatologic
- Behcet's Syndrome
- Reiter's Syndrome
- Crohn's Disease
- Systemic Lupus Erythematosus (often painless ulcers on Palate)
- Discoid Lupus Erythematosus
- Sarcoidosis
- Granulomatosis with Polyangiitis (previously known as Wegener's Granulomatosis)
