Oral leukoplakia and oral lichen planus: a white patch in the mouth, symptoms, risk and treatment

What is oral leukoplakia?

Oral leukoplakia is a white patch or patches on the lining of the mouth that cannot be wiped or scraped off. The NHS describes them as usually painless, irregular in shape, sometimes slightly raised and with red areas, found most often on or under the tongue, and also on the cheeks, gums, floor of the mouth or palate.

Leukoplakia is diagnosed by exclusion. Van der Waal (2015) defines it as a predominantly white lesion that cannot be attributed to any other disease, and with white lesions of known cause, such as friction or a sharp filling, the final diagnosis is made only after the cause has been removed and 4 to 8 weeks have passed.

Experts at a World Health Organization (WHO) collaborating centre classify leukoplakia as an oral potentially malignant disorder, meaning a condition in which the risk of cancer is higher than in healthy mucosa. A meta-analysis by Mello et al. (2018) estimated the prevalence of leukoplakia in adults at 4.11%, and a review by Lonni et al. (2026), which did not include lichen planus, identifies it as the most common potentially malignant disorder in Europe.

Doctors distinguish homogeneous leukoplakia, which is thin, flat and evenly white, from non-homogeneous leukoplakia, which may have red areas, nodules or a warty, uneven surface, even when it is entirely white (van der Waal, 2015). The authors of the review by Pimenta-Barros et al. (2025) point out that the red areas in non-homogeneous leukoplakia may correspond to more severe dysplasia, which is why this distinction matters for the risk.

What is oral lichen planus, and what are its symptoms?

Oral lichen planus is a chronic inflammatory disease of the lining of the mouth in which the immune system attacks the body’s own tissue. Cleveland Clinic describes two main forms: reticular, with white dots, patches or thread-like lines, usually painless, and erosive, with bright red, irritated gums and ulcers, in which eating, drinking and brushing hurt.

The NHS lists white patches on the gums, tongue and inside of the cheeks and a burning feeling in the mouth, especially when eating and drinking, and notes that lichen planus in the mouth can last for years. Symptoms often come back in flare-ups, and the pain is made worse by sour, spicy, salty and crunchy foods.

A meta-analysis by González-Moles et al. (2021) estimated the prevalence of oral lichen planus at 1.01% worldwide and 1.43% in Europe, with a clear rise after the age of 40. Cleveland Clinic reports that women are affected 3 to 4 times more often than men, and that most diagnoses are made between the ages of 30 and 70.

Lichenoid lesions, which are reactions to certain medicines or dental materials, look similar. The review by Müller (2019) describes how a lesion lying against an amalgam filling can resemble lichen planus and clear up after the filling is replaced, which is why the dentist checks whether a white lesion touches an old filling.

A white patch in the mouth: what else can cause it?

A white patch in the mouth has many possible causes. The review by Müller (2019) stresses that most lesions that look white are benign, and a common example of a reactive lesion is frictional keratosis: a white line or rough area on the cheek along the line where the teeth meet, in people who bite or suck their cheek.

Frictional keratosis clears up once the habit stops, while thrush produces a white coating which, according to the NHS, can be wiped off to reveal red, sometimes bleeding mucosa. The table sets out the features a dentist uses for a first distinction between these lesions; the final diagnosis of a lesion that does not clear up comes from a histopathological examination.

Is leukoplakia cancer?

Leukoplakia is not cancer, but it increases the risk of cancer developing, which is why it needs monitoring. The meta-analysis by Pimenta-Barros et al. (2025) covered 55 studies and 41,231 people with leukoplakia and estimated malignant transformation at 6.64%; an earlier review by Aguirre-Urizar et al. (2021) gave 9.8%.

The risk is not the same for everyone. According to the review by Pimenta-Barros et al. (2025), non-homogeneous leukoplakia turned into cancer 4.23 times more often than homogeneous leukoplakia, the risk also rose with larger lesions, in smokers and with epithelial dysplasia on histopathological examination, and leukoplakias on the side of the tongue became cancerous in 12.71% of cases.

In individual studies, according to the review by Aguirre-Urizar et al. (2021), the transformation rate ranged from 1.1 to 40.8%, so averaged figures need to be read with caution. They do mean, however, that most leukoplakias do not turn into cancer, and the point of monitoring is to catch a lesion that starts to look different. The symptoms of oral cancer itself are described in a separate article.

Can lichen planus turn into cancer?

Oral lichen planus rarely turns into cancer. The meta-analysis by González-Moles et al. (2019), covering 82 studies and 26,742 patients, reported malignant transformation in 1.14% of cases, more often with lesions on the tongue and in the atrophic-erosive form.

The review by Idrees et al. (2021), which applied stricter diagnostic criteria, counted transformation in only 0.44% of 12,838 patients. In that review the risk was clearly higher in smokers, people who drink alcohol and those infected with the hepatitis C virus.

These data show that lichen planus is not a reason for alarm, but it is a reason for check-ups. Cleveland Clinic recommends regular visits even when lichen planus causes no symptoms, and a lesion that starts to grow, bleeds or changes its appearance is worth showing to a dentist without waiting for the next scheduled check-up.

How does a dentist assess a white lesion, and when is a biopsy needed?

The dentist starts by looking at and feeling the lesion and by ruling out simple causes, such as thrush or cheek biting, as the NHS describes. When the cause may be friction, a sharp edge of a tooth or a denture, it is removed and the lesion is assessed again after a few weeks.

A white lesion that does not clear up after the cause has been removed usually needs a biopsy, that is taking a small piece of tissue for histopathological examination. The examination shows whether there is dysplasia, meaning abnormal cells, in the epithelium, and this affects what happens next: in the review by Lonni et al. (2026), dysplasia was found in 46.21% of confirmed potentially malignant disorders.

With lichen planus, Cleveland Clinic reports that a doctor can often recognise it by its appearance, and a biopsy confirms the diagnosis and rules out other diseases. A red or red and white patch needs urgent assessment: the UK’s NICE guideline recommends that such a lesion be assessed by a dentist urgently.

How are leukoplakia and lichen planus treated?

Treatment of leukoplakia depends on the result of the histopathological examination and on where the lesion is. The NHS says treatment is not always needed but regular check-ups are, and a lesion that may turn into cancer is removed surgically, with a laser or a scalpel, under local or general anaesthesia.

A 2016 Cochrane review (Lodi et al., 14 studies, 909 participants) found no treatment proven to prevent cancer developing in people with leukoplakia, and it included no randomised trials comparing excision of the lesion with observation. Such trials were published later: according to Arduino et al. (2021), regular check-ups are a reliable standard of care for leukoplakia without dysplasia, while preliminary results from Lombardi et al. (2025) point to a higher risk of cancer when dysplastic lesions on the tongue are only observed. Excision does not rule out cancer in the future and does not replace check-ups. The simplest step remains stopping tobacco and cutting down on alcohol, after which, according to the NHS, the patch may shrink or even disappear.

Lichen planus cannot be cured, but its symptoms can be eased, and when it causes no trouble treatment may be unnecessary. A 2020 Cochrane review (Lodi et al., 35 studies, 1,474 participants) found that topical corticosteroids may relieve pain more often than placebo, although the certainty of this evidence is low; the medicine and how to use it are chosen by the doctor.

• With lichen planus, avoid salty, spicy and sour foods and alcohol if they make the burning worse (NHS).
• Brush your teeth carefully twice a day with a soft toothbrush to keep your gums healthy.
• Choose an alcohol-free mouthwash and a mild toothpaste without a strong flavour if ordinary products sting.
• Do not smoke or use chewing tobacco; with leukoplakia, the NHS advises this as the first step.
• Come for check-ups at the intervals agreed with your doctor, even when the lesion causes no symptoms.

How it works at DentalBlue

At DentalBlue in Białystok, a white lesion in the mouth is assessed by a dentist during a “Wizyta bez bólu” (visit without pain), which includes a panoramic X-ray, a consultation, an examination and a written treatment plan; in the clinic’s price list it costs 300 zł. If the lesion needs to be removed, the price list includes “Usunięcie zmiany na błonie śluzowej” (removal of a mucosal lesion, 500 zł) and “Badanie histopatologiczne” (histopathological examination, 100 zł). Surgical procedures are carried out under local anaesthesia or, for patients who qualify, under general anaesthesia. The final scope and cost are set by the dentist, and prices may change. When the test result or the appearance of the lesion requires it, further treatment is provided by a specialist clinic.