Dentists and physicians split canker sores into three distinct classes. Knowing which type of canker sores that you have can help you prepare for what to expect, when to seek medical attention, and what complications may occur.

Minor aphthous ulcers: canker sores in mouth

The mildest and most common canker sores are called minor aphthous ulcers. Eight out of ten people with canker sores have minor aphthous ulcers. These canker sores in mouth are quite small, usually only an eighth of an inch in diameter. They form a simple ulcer, or depression, in the tissue. Minor sores only last one to two weeks and usually disappear with or without treatment. While this may seem like a short time, canker sores last longer than most other mouth sores and are generally more painful. When minor aphthous ulcers do finally go away, they do not leave a scar.

Major aphthous ulcers: scarring canker sores in mouth

Unlike minor lesions, major aphthous ulcers may leave a scar in the mouth. Major canker sores are much larger on average, growing to a half an inch in diameter or more. Instead of just being a simple ulcer, these major canker sores may have a raised border encircling the lesion. Unlike milder forms of the disease, major canker sores may cause systemic symptoms such as fever and malaise.

Major aphthous ulcers also remain in the mouth longer than minor sores. Expect major aphthous ulcers to remain for more than two weeks and usually up to four weeks. Since major aphthous ulcers are so big, the affected skin does not readily heal, which leaves scar tissue in the mouth. Major aphthous ulcers have also be called periadenitis mucosa necrotica recurrens or Sutton’s disease. About one in ten patients with canker sores will have major lesions.

Herpetiform canker sores

Many of us have heard the term herpes, especially genital herpes, but herpetiform aphthous ulcers are completely unrelated. The term herpes simply refers to a skin lesion that “creeps” but generally applies to any skin condition which appears like a clustering of small bumps or blisters. In the case of herpetiform canker sores, the individual lesions are quite small, smaller than even minor aphthous ulcers. However they cluster in large groups of several dozen making the overall size of the lesion quite large. Fortunately herpetiform canker sores do not leave scars and disappear in about two weeks. Curiously, this type of canker sore occurs most often in women and first occurs later in life then other types. In fact, it is very rare to see herpetiform canker sores in children. Moreover, herpetiform aphthous ulcers are the rarest type of canker sore making up only about 5% of all canker sore cases.

The natural course of the disease may include more than one type of canker sore

It may be the case that more than one type of canker sore can occur in the same patient and in the same mouth. Patients may begin with a minor aphthous ulcer that can progress to a major lesion. Likewise, when a person has had one type of canker sore in the past, it does not necessarily predict what type that patient will have in the future. On the other hand, herpetiform aphthous ulcers may unite and form larger lesions without discrete borders. In this case the lesion may look like a major aphthous ulcer but is not, either in its potential to scarring or in its prognosis.

Reference

Scully C, Gorsky M, Lozada-Nur F. The diagnosis and management of recurrent aphthous stomatitis: a consensus approach. J Am Dent Assoc 2003;134:200-207.