Derm Dx: A painful sore on the inner lip


  • Aphthous Ulcer_0413 Derm Dx

A 31-year-old Asian male complains of painful sores in his mouth that appear every few months. Each eruption produces approximately two to five lesions and lasts about 10 days.

The patient is otherwise healthy and takes no medications. He says the sores usually appear on his inner lip.

Recurrent aphthous stomatitis is synonymous with 'canker sores' and 'aphthous ulcers.' The condition is common, affecting as many as 10% to 50% of individuals.  There are several categories of aphthae: Minor aphthae are the most common form. Lesions appear as...

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Recurrent aphthous stomatitis is synonymous with ‘canker sores’ and ‘aphthous ulcers.’ The condition is common, affecting as many as 10% to 50% of individuals. 

There are several categories of aphthae:

Minor aphthae are the most common form. Lesions appear as round or oval ulcers less than 5mm in diameter. The ulcers are well demarcated, covered by a whitish pseudomembrane and surrounded by a red rim.  

Minor aphthae are only located on non-keratinized oral mucosa. This included the mucosa of the cheek and lip, the floor of the mouth, the undersurface of the tongue and the soft palate.  These aphthae spare the keratinized oral mucosa, such as the alveolar gingival (the part of the gums that overlie the bone), the dorsum of the tongue and the hard palate.

Minor aphthae heal without scarring in seven to 14 days. Recurrence is variable. Certain individuals will rarely experience recurrence, whereas others may be almost continually suffer from crops of the ulcers. 

Major aphthae differ from minor aphthae in that they are larger (>1cm), deeper, last longer (up to 6 weeks) and may heal with scarring. Pain is significant. 

Herpetiform aphthae is a rare variant. Multiple small, painful, grouped ulcers appear which may resemble primary herpes gingivostomatitis. Herpetiform apthae affect keratinized oral mucosa, whereas other aphthae spare keratinized mucosa. 

Although aphthae are most common in the mouth, they may also occur on the vagina, vulva, penis, anus and conjunctiva. The term ‘complex aphthosis’ refers to either the constant presence of more than three oral aphthae, or the concomitant presence of both oral and genital aphthae. 

The pathogenesis of aphthae is poorly understood. Recurrences may be triggered by stress, allergy, food hypersensitivity, trauma or hormal changes. There is controversy as to the role of vitamin and nutritional deficiencies in ulcer recurrence.

Many disorders are associated with aphthae including Behçet’s disease, HIV infection, inflammatory bowel disease, cyclic neutropenia and the autoinflammatory syndromes. It may be clinically appropriate to rule out an underlying cause, particularly in the case of complex aphthosis.

Treatment consists of managing pain, promoting healing and preventing recurrences.  Topical anesthetics such as viscous lidocaine or benzocaine gel may be helpful for pain management. 

Topical corticosteroids such as clobetasol gel or triamcinolone dental preparation applied to the lesions several times daily help promote healing.  In severe cases, oral medications such as colchicines, dapsone or thalidomide can be used to prevent recurrences. 

Adam Rees, MD, is a graduate of the University of California Los Angeles School of Medicine and a resident in the Department of Dermatology at Baylor College of Medicine in Houston.


  1. Bolognia J, Jorizzo JL, Rapini RP. “Chapter 71 – Oral Disease.” Dermatology. St. Louis: Mosby/Elsevier, 2008.
  2. James WD, Berger TD, Elston DM et al. “Chapter 28: Dermal and Subcutaneous Tumors.” Andrews’ Diseases of the Skin: Clinical Dermatology. Philadelphia: Saunders Elsevier, 2006.
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