Aphthous ulcers can be classified based on size and number.
(1) size in diameter
Diameter in mm
2 - 8 mm
1 to 6
> 8 mm (up to 30 mm)
1 or 10
1 - 2 mm
numerous (may be > 100), with wider distribution
• Some authors use 10 mm as the cutoff distinguishing minor from major aphthae.
• Major aphthous ulcers can heal by scarring, which is not seen in the other types.
• Herpetiform aphthous ulcers have no relation to Herpes simplex virus.
• Herpetiform ulcers may occur in "crops", with a new crop appearing before a previous crop has completely resolved.
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