Leukoplakia: Causes, Types, Diagnosis, and Treatment

Posted on Jan 6, 2025 in Biomedical Sciences

Leukoplakia: A Comprehensive Review

Definition

Leukoplakia is a white patch or plaque that cannot be characterized clinically or pathologically as any other disease.

Modified Definition (Malmo, Sweden, 1983)

A white patch or plaque that cannot be characterized clinically or pathologically as any other disease and is not associated with any physical or chemical agent except the use of tobacco.

Etiology: Local Factors

  • Tobacco products (smoked and smokeless)
  • Alcohol
  • Chronic irritation
  • Candidiasis
  • Electrogalvanic reactions
  • Possibly HSV and HPV

Clinical Features

  • Males > 50 years
  • Common Sites: Buccal mucosa, vermilion border of the lower lip, gingiva
  • Less Common Sites: Palate, maxillary mucosa, retromolar area, floor of the mouth, tongue
  • 90% of cases in the floor of the mouth and tongue show dysplasia or carcinoma

Types of Leukoplakia

  • Homogenous
  • Non-homogenous:
    • Speckled or Nodular
    • Verrucous
    • Proliferative Verrucous

Homogenous Leukoplakia

  • Well-defined white patch, localized or extensive
  • Slightly elevated
  • Wrinkled, corrugated, or fissured
  • Leathery or cracked mud feeling on palpation

Nodular or Speckled Leukoplakia

  • Non-homogenous
  • Mixed lesion with white nodules or patches on an erythematous background
  • Higher malignant transformation rate

Verrucous Leukoplakia

  • Thick with papillary projections
  • Heavily keratinized
  • > 60 – 80 years
  • Exophytic growth pattern

Proliferative Verrucous Leukoplakia

  • Extensive papillary or verrucous plaques
  • Slow, extensive involvement
  • High potential for malignant transformation

Diagnosis

  1. Clinical criteria: Location, appearance, known irritants, clinical course
  2. Differential diagnosis: Exclusion of other white lesions
  3. Chairside tests: Vital tissue staining, exfoliative cytology (brush biopsy), chemiluminescence
  4. Biopsy and histopathology: Confirmatory

Differential Diagnosis

  • Keratotic lichen planus (reticular lichen planus)
  • Pseudomembranous candidiasis
  • Hypertrophic candidiasis
  • Syphilitic glossitis (in case of leukoplakia of the tongue)
  • Sideropenic dysphagia
  • White spongy nevus

Histopathology

  • Benign Leukoplakia: Hyperkeratinization, with or without acanthosis; chronic inflammation (80% of cases)
  • Dysplastic changes and carcinoma in situ (17% of cases)
  • Carcinoma (3% of cases)

Management

Prevention and removal of irritants may lead to regression, requiring no further treatment. Recall visits are recommended every 6 months to 1 year. If there is no regression, surgical excision, laser therapy, or cryosurgery may be considered. Vitamin A analogues and bleomycin have also been used.

Radiation Sensitivity and Cell Type

Different cells react to radiation in different ways. The most sensitive cells have a high mitotic index and undergo many future mitoses, and are most primitive in differentiation.

Sensitivity of Mammalian Cells to Radiation

  • Vegetative intermitotic cells
  • Differentiating intermitotic cells
  • Multipotential connective tissue cells
  • Reverting postmitotic cells
  • Fixed postmitotic cells

Stem Cells (Vegetative Intermitotic Cells)

These are the most sensitive cells to radiation. They are constantly dividing, have a long mitotic future, and do not differentiate. Examples include spermatogonia, erythroblasts, and basal cells of the oral mucous membrane.

Differentiating Intermitotic Cells

These are less sensitive than stem cells. They divide less frequently and show some differentiation. Examples include epithelial cells, spermatocytes, oocytes, and hematopoietic lineage.

Multipotential Connective Tissue Cells

These have moderate sensitivity to radiation. They divide regularly upon demand and are capable of limited differentiation. Examples include endothelial cells, fibroblasts, and mesenchymal cells.

Reverting Postmitotic Cells

These cells are resistant to the direct action of radiation. They do not replace specialized cells. Examples include salivary gland duct cells, liver, kidney, and thyroid cells, and parenchymal cells.

Fixed Postmitotic Cells

These are the most resistant to radiation. They are the most differentiated and cannot divide when mature. Examples include neurons, smooth muscle cells, and squamous epithelium.