Leukoplakia and White Tongue: Causes, Symptoms, Risks, and Treatment

What is Leukoplakia and White Tongue?

Leukoplakia is a characteristic lesion of the oral cavity. It is defined by the formation of a thickened, whitish plaque on the mucous membranes, caused by abnormal and excessive keratinization (hardening) of the epithelium. The epithelium is the thin layer of cells that lines the mouth and other body surfaces.

Leukoplakia most commonly develops:

• In the oral cavity in approximately 98% of cases;
• More rarely on the genitals, pharynx, or larynx (throat).

Leukoplakia is classified as a pre-neoplastic (precancerous) condition. This means that if it is not identified and treated promptly, it carries a risk of evolving into a malignant tumor, specifically oral squamous cell carcinoma. This type of cancer has a serious prognosis.

This distinction from a simple white tongue coating is critical: while a white coating on the tongue is usually harmless and temporary, true leukoplakia requires medical evaluation, biopsy, and close follow-up.

---

Causes

The primary and most established cause of leukoplakia is tobacco use. This includes cigars and pipe smoking, but cigarettes are also a significant risk factor. The link between smoking and leukoplakia has been extensively demonstrated in the scientific literature. Perhaps the most compelling evidence of this causal relationship comes from the observation that complete smoking cessation can lead to regression of established leukoplakia lesions, especially in their early stages.

Leukoplakia has a slightly higher incidence in males, historically linked to greater tobacco and alcohol consumption in this demographic. The peak onset of the condition typically occurs after the age of 50.

Risk Factors

Beyond tobacco use, several additional risk factors have been identified that may predispose an individual to developing leukoplakia:

• Alcohol abuse, especially when combined with smoking, significantly raises the risk.
• Systemic conditions, including:
  • Diabetes mellitus
  • Hepatic (liver) and renal (kidney) diseases
  • HIV/AIDS
  • Immunosuppression from any cause (e.g., immunosuppressive medications, chemotherapy)
• Oral cavity infections (bacterial, viral, or fungal)
• Chronic mechanical irritation of the oral mucosa from:
  • Ill-fitting dental prostheses or dentures
  • Chipped or broken teeth with sharp edges
  • Trauma from habitual cheek biting or abnormal chewing habits
  • Orthodontic appliances
• Inhalation of fine particulate matter (occupational or environmental exposure)
• Exposure to heavy metals
• Ingestion of caustic substances
• Drug reactions (rare)

Important: The co-occurrence of smoking and alcohol consumption is particularly dangerous. These two risk factors act synergistically, meaning they multiply rather than simply add to the individual risk of oral leukoplakia and oral cancer.

White Coating on the Tongue

A white coating or film on the tongue is a separate and distinct condition from leukoplakia and should not be confused with it. From a compositional standpoint, a white tongue coating usually forms when certain substances build up between the taste buds and papillae. These may include:

• Bacteria
• Food debris
• Dead cells
• Fungi

This buildup often leads to the characteristic white appearance.

While the appearance of a white tongue may seem alarming, the underlying cause is usually temporary and rarely serious, most often linked to behavioral or lifestyle factors:

Lifestyle and environmental factors:

• Insufficient oral hygiene
• Dehydration and/or xerostomia (dry mouth)
• Smoking
• Excessive alcohol consumption
• Mouth breathing (e.g., due to conditions causing nasal congestion)

Medical conditions:

• Viral syndromes, such as the common cold or influenza, are often associated with fever.
• Oral thrush (candidiasis/mughetto), a fungal infection, is particularly common in immunocompromised patients or those taking antibiotics.
• Scarlet fever
• Geographic tongue
• Other systemic conditions

For a more detailed discussion of white tongue specifically, refer to the dedicated article.

---

Symptoms

Leukoplakia can develop at the following anatomical sites:

Oral cavity (98% of cases):

• Tongue (particularly the lateral borders)
• Inner surface of the lips
• Gums (gingiva)
• Floor of the mouth
• Inner surface of the cheeks (buccal mucosa)
• Hard and soft palate

External genitalia:

• In males: glans penis and foreskin (prepuce)
• In females: labia minora and majora, vulva, clitoris, and vaginal walls

Pharynx and larynx (throat)

Oral Symptoms

When leukoplakia develops in the oral cavity, it may cause:

• Altered taste
• Itching or burning sensations
• Difficulty chewing
• Dysphagia (difficulty swallowing), particularly when the lesion involves the pharynx
• Pain, especially in ulcerated forms
• Aesthetic concerns due to the visible lesion

Morphological Classification and Cancer Risk

From a clinical and morphological perspective, leukoplakia is classified into three main types. Each type carries a different risk of malignant transformation.

🔴 Cancer risk: Approximately 10% of leukoplakia lesions carry a significant risk of malignant transformation, with an average evolution time of approximately 10 years. However, lesions with ulceration, induration (hardness), or rapid growth should be evaluated urgently, as the risk in these cases may be much higher.

The presence of erythroplakia, or red patches, within or near a leukoplakic lesion (sometimes called erythroleukoplakia) is linked to a much higher risk of cancer. Because of this risk, immediate specialist evaluation is required.

---

Diagnosis

The diagnosis of leukoplakia is fundamentally a diagnosis of exclusion. This means that before leukoplakia can be confirmed, every other possible cause of a whitish oral plaque must be ruled out. These include oral candidiasis, lichen planus, syphilitic mucous patches, chemical burns, and other benign conditions.

When a suspicious lesion is found, the patient should promptly consult a physician or oral medicine specialist. The evaluation includes:

Clinical Assessment

The clinician will take a detailed medical history (anamnesis) and perform a thorough physical examination of the lesion, evaluating:

• Whether it is flat, raised, nodular, ulcerated, or fissured
• Its size and any change in size over time
• Whether it causes pain, itching, or functional impairment (difficulty chewing, swallowing)
• Its exact anatomical location(s) and whether it affects multiple sites

Biopsy and Histopathological Examination

A biopsy is mandatory for definitive diagnosis. This involves removing a small tissue sample from the lesion for microscopic analysis by a pathologist.

Histopathological examination is the critical step that distinguishes:

• Benign hyperkeratosis (no atypia): close monitoring and elimination of risk factors
• Mild to moderate epithelial dysplasia: requires treatment and close surveillance
• Severe dysplasia or carcinoma in situ: requires immediate surgical intervention
• Invasive squamous cell carcinoma: requires oncological treatment

🔬 A biopsy should be taken from the most clinically suspicious area of the lesion. This is often an area that appears red, ulcerated, or indurated rather than simply white.

---

Treatment

As a potentially pre-malignant lesion, leukoplakia must be recognized and managed promptly. The therapeutic approach depends on the type, size, and histological findings of the lesion.

Smoking Cessation

There is evidence that complete smoking cessation can lead to regression of leukoplakia. For example, studies on early-stage, small lesions demonstrate this effect. This underscores the central role of tobacco in the pathogenesis of the condition, and smoking cessation is always the first and most important step in management, regardless of any other treatment undertaken.

Surgical Removal

In the vast majority of cases, especially when spontaneous regression has not occurred or seems unlikely, the preferred treatment is complete surgical excision of the lesion.

Removal can be achieved using:

• Conventional surgery (scalpel excision)
• Laser ablation (CO₂ or Er:YAG laser), which is associated with excellent precision and good healing.
• Cryosurgery, used in selected cases

The entire lesion must be removed (excision in toto), and the specimen is submitted for histopathological analysis of the surgical margins to confirm complete removal.

Post-Surgical Management and Oncological Follow-up

If histopathological examination of the excised tissue reveals the presence of neoplastic (cancerous) cells, the patient must be referred immediately to a multidisciplinary oncological team. Further treatment is then planned to ensure oncological radicality, meaning the complete eradication of the cancer. This may include:

• Wider surgical re-excision with adequate margins
• Radiation therapy
• Chemotherapy (in more advanced cases)

Long-Term Surveillance

Even after successful treatment, patients with a history of leukoplakia require regular and lifelong follow-up with a specialist, given:

• The risk of local recurrence of leukoplakia
• The risk of developing a second primary oral cancer at a different site
• The ongoing risk associated with persistent habits (smoking, alcohol)

All patients should also be counseled on eliminating all modifiable risk factors. For example, quitting tobacco and alcohol use is the single most effective measure for preventing recurrence and reducing cancer risk.

---

Sources and Bibliography

• Warnakulasuriya S, et al. Oral leukoplakia and tobacco smoking: a dose-response relationship. Journal of Oral Pathology & Medicine. 2001.
• Silverman S Jr, et al. Malignant transformation of oral leukoplakia and regression following cessation of tobacco use. Journal of the American Dental Association. 1976.
• Mithani SK, et al. Molecular genetics of premalignant oral lesions and regression following tobacco cessation. Head & Neck. 1999.
• van der Waal I. Oral leukoplakia, the ongoing controversy. British Journal of Oral and Maxillofacial Surgery. 2021;59(4):362–368.
• World Health Organization (WHO). Classification of Tumours of the Head and Neck. 5th ed. Lyon: IARC Press, 2022.
• Warnakulasuriya S, Ariyawardana A. Malignant transformation of oral leukoplakia: a systematic review of observational studies. Journal of Oral Pathology & Medicine. 2016;45(3):155–166.