Aphthous Ulcer; Minor, Major and Herpetiform Aphthous Ulcer Detailed Comparison
Minor aphthous stomatitis:
Represents the most common form; minor aphthae are less than 1 cm in diameter and can be single or multiple.

The ulcers are round, shallow, and often symmetric. Once present, they can be painful (mainly during the first 3–4 days, exacerbated with oral function), usually last 7–10 days, and heal without scarring.
The majority of patients with RAS report one to six lesions at a time with few recurring episodes in 1 year.

Major aphthous ulcers
Major aphthous ulcers are larger (usually >1.0 cm in diameter), deep, extremely painful lesions, which interfere with speech and eating, and last for weeks or months.

In some cases, major aphthae may be misdiagnosed as a vesiculobullous disorder, squamous cell carcinoma, or granulomatous disease.
The lesions may heal with scar formation. In the most severe cases, hospitalization for intravenous feeding may be required.
Herpetiform aphthous stomatitis
Herpetiform aphthous stomatitis is a rare variant, with multiple small ulcers, measuring a few millimeters, with a crop-like appearance.
It usually coalesce to form a large lesion with irregular margin similar to HSV-related ulcers.

The overall appearance is identical to the minor aphthous ulcers (although smaller in size), and these also heal within 7–10 days.
Severe aphthous ulcers
Severe aphthous ulcers These are a variant in which patients are almost never ulcer-free, and they are often associated with chronic pain, malnutrition, and weight loss.
Patients typically develop new ulcers when the previous ones are healing.

Both the keratinized and nonkeratinized mucosa may be affected.
In HIV patients, severe recurrent aphthous ulcers are often larger than 1.0 cm in diameter
[…] Aphthous Ulcer; Minor, Major and Herpetiform Aphthous Ulcer Detailed Comparison […]