Some disorders of the skin and inner lining of cavities like the mouth seem like harmless abnormalities that do not warrant much medical attention. Apart from moderate discomfort, it does not appear to cause any damage to tissue or affect functioning. Oral leukoplakia is one such condition. However, it needs to be carefully monitored as it has the potential to become malignant (cancerous).
What is oral leukoplakia?
Oral Leukoplakia (OL) describes the appearance of white or gray patches on the in the mouth cavity – on the inner cheek, tongue and gums. Typical leukoplakia plaques may appear inside mouth that do not get scraped off easily. The cause of oral leukoplakia remains unclear but it seems like to persistent irritation of the tissue of the mouth. Although harmless, oral leukoplakoa patches have a high risk of becoming malignant (cancerous). It is therefore considered as a pre-malignant clinical sign. Another form that appears as fuzzy, hairy patches called hairy leukoplakia appear during severe viral infections like HIV. Oral leukoplakia affects 1% of the population, mainly people above 40 years, and the elderly in particular.
Oral Leukoplakia Pathophysiology
Inner lining of the mouth
The soft thin tissue that covers the mouth cavity is called the oral mucosa. It protects the underlying tissues like muscles, fats, nerves and blood vessels from mechanical injury. It is thin and almost transparent and has a red color due to the blood flow in the superficial blood vessels just underneath it. Although mucus glands secrete small amount of mucus, the oral mucosal membrane is largely kept moist by saliva secreted from the major salivary glands.
Injury to the oral mucosa
Injury of any form causes tissue become inflamed which is then followed by healing and tissue regeneration. Although the cause of oral leukoplakia is unknown, it appears to be linked to ongoing injury. Persistent irritation of the mouth mucosal membrane usually elicits development of oral leukoplakia lesions. Often diagnosed in the tobacco users, it appears that tobacco and the range of chemicals within it act as a major irritant to the moral mucosa. Certain infectious diseases like AIDS also present unusual, fuzzy or hairy lesions known as hairy leukoplakia. Hairy leukoplakia is often indicates a weak immune system and is among the first signs of viral infections including HIV. Although harmless initially, oral leukoplakia patches may become malignant and develop into oral cancers.
Skin protein clumps
Keratin deposition or keratinization usually marks the maturity of epidermal skin cells that makes it strong and resistant to injury. Mucosal lining of the mouth, unlike skin cells, is soft and contains relatively less keratin. Oral epithelium is frequently subjected to mechanical injuries including chewing and denture fittings. Rapid turnover rates and regenerative abilities compensate for the absence of keratinization. Excessive keratin deposition in mouth epithelium often appears as white plaque, a characteristic feature of typical oral leukoplakia patch which is markedly different from the surrounding red oral mucosa.
Oral Leukoplakia Causes
The causes of oral leukoplakia remain unclear. However, certain events are linked to its appearance :
- Excessive and prolonged use of tobacco (smoking or chewing).
- Abrasions from rough teeth or ill-fitting dentures, fillings or crown and chewing areca nut and betel leaf.
- Viral infections like HIV or AIDS.
- Deficiency of vitamins – A, B12, C and folic acid in the blood.
- Endocrine disturbances
- Exposure to sun
Although tobacco is considered to be the major contributor of oral leukoplakia, none of its individual biochemical components have been isolated as the sole irritant that could cause these lesions. Men are at twice the risk of developing oral leukoplakia as compared to females.
Oral leukoplakia patches resemble thrush that appears commonly in the mouth of patients suffering from diabetes, HIV or cancer due to accumulation of fungus (candida). Thrush, like hairy leukoplakia, indicates a weak immune system optimum for harboring viral infections. Unlike oral leukoplakia lesions, thrush presents creamy, painful patches that bleed upon scraping.
Most oral leukoplakia lesions are of unknown origin (idiopathic). Idiopathic oral leukoplakia patches are considered as precursors of oral cancers (pre-malignant lesion) and warrant a regular check up (biopsy) every 2 to 3 months. Excessive tobacco and alcohol consumption are important risk factors related to transformation of oral leukoplakia into malignant cancers. Oral leukoplakia contributes to 20% of the total oral cancers detected.
Oral Leukoplakia Symptoms
The development of oral leukoplakia patches is progressive starting from small, translucent patch to prominent, slightly raised, opaque white plaque with granular texture.
Usually without symptoms, oral leukoplakia manifests itself as:
- White or gray sores in the cheek wall, floor and roof of the mouth or on tongue, gums and lips.
- Thick, slightly raised, hardened mass of skin cells having rough texture that could not be scraped off.
A variation of oral leukoplakia is hairy leukoplakia. It manifests itself as hairy or fuzzy skin patches in the mouth. Usually hairy leukoplakia patches appear during viral infections like HIV/AIDS.
Instead of white or gray patches, rarely red sores (erythroplakia) appear. Erythroplakia patches have abnormalities in maturation of epidermal cells (dysplasia). The absence of outer epithelial lining, reveal the underlying blood vessels making these lesions appear red-colored. They are highly potent of becoming cancerous.
Oral Leukoplakia Pictures
The oral leukoplakia pictures are typical presentations of the condition. However, it is important to note that these lesions should be investigated further by a medical professional before reaching a diagnosis of oral leukpoplakia. Various conditions or the mouth and oral mucosa may appear in a similar manner and these pictures should not be used as a guide for self diagnosis.
Pictures of oral leukoplakia from Wikimedia Commons
Oral Leukoplakia Types
Based on their malignant potentials, clinically, oral leukoplakia is divided into two categories:
- Homogenous oral leukoplakia comprises of uniform white plaques, prominent in the lining of the mouth. Least malignant.
- Verrucuos or speckled OL are small white nodules on smooth, red tissue of tongue, cheek or palate. It is considered to be a transition between leukoplakia and erythroplakia (or erythroplasia), which is more prone to become malignant.
Oral Leukoplakia Diagnosis
Typical oral leukoplakia patches are harmless and develop slowly over few weeks to months. Patches are usually painless but may be sensitive to touch, heat, spicy food or any other cause of irritation.
A biopsy test of the cells from oral leukoplakia lesion could confirm the nature of lesion and help in ruling out the possibility of oral cancer. Idiopathic oral leukoplakia lesions should be monitored carefully as they could serve as important prognostic indicator of oral cancers. Independent studies suggest that rigorous monitoring for 2-3 years, after the initial oral leukoplakia diagnosis, may be important for studying malignancy-related developments.
Oral Leukoplakia Differential Diagnosis
Oral leukoplakia plaques are clinically different from mouth lesions present in other conditions or diseases like:
- Chemical burns
- Typical mouth ulcers indicating gastrointestinal disturbances
- Other leukoplakia present during infections like candidal and syphilitic leukoplakia, including hairy leukoplakia that indicates viral infections like HIV or Epstein-Barr virus
- Congenital lesions (white-sponge nevus, dyskeratosis congenital, pachyonychia congenita)
- Common skin-related problems that present as pre-disposing conditions to cancers like keratoses, oral submucous fibrosis, lupus erythematosus or frank carcinomas.
Oral Leukoplakia Cancer Risk
Clinical criteria demonstrating a high risk of malignant transformation of oral leukoplakia patches are:
- Appearance of verrucous type of oral leukoplakia
- Formation of ulcers within the lesions
- Presence of nodules
- Lesions with hard periphery indicating abnormal maturation of epidermal cells (dysplasia)
- Lesions at the sides and under-surface of tongue and anterior floor of mouth
Oral Leukoplakia Treatment
Usually removing the source of irritation offers the best treatment for oral leukoplakia.
- Repairing the dentures and rough teeth surfaces.
- Reducing tobacco and alcohol consumption.
- Beta-carotene, as oral supplement, tends to improve and accelerate healing of oral leukoplakia patches.
- Retinoids that arrest abnormal cell-growth and are potent anti-acne, could reduce progression of oral leukoplakia lesions into malignant tumors.
- Treatment of hairy leukoplakia patches requires antiviral medication.
Oral leukoplakia resolves spontaneously within a few weeks to months after removal of the cause. However, few oral leukoplakia patches need to be surgically removed.