Hyperkeratosis: thickening of keratin layer. Acanthosis



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White lesions
Mutaz Ali Hassan

University of Khartoum



Faculty of Dentistry

  • Causes of white lesions

  • Hyperkeratosis: thickening of keratin layer.

  • Acanthosis: epithelial hyperplasia due to increase in spinous cell layer..

  • Spongiosis: Intracellular epithelial edema.

  • Reduced vascularity of underline connective tissue.

  • Submucosal deposits: tumors or anomalies.

  • Surface debris or fibrinous exudate.

  • Fungal colonies.

  • Classification

  • Developmental conditions.

  • Hereditary diseases.

  • Reactive lesions.

  • Infective lesions.

  • Immunologically-mediated conditions.

  • Premalignant lesions & conditions.

  • Non-epithelial white-yellow lesions.

  • Neoplastic lesions.

  • Fordyces granules.

  • Ectopic lymphoid tissue.

  • Hereditary conditions.

  • Leukoedema.

  • White sponge nevus.

  • Hereditary benign intraepithelial dyskeratosis.

  • Follicular keratosis (Darriers disease).




  • Reactive lesions.

  • Mechanical: frictional keratosis, lip and cheek biting.

  • Physical: thermal burns, electric burns, radiation mucositis.

  • Nicotinic stomatitis.

  • Hairy tongue.

  • Tooth paste-associated slough.

  • Chemical: mucosal aspirin burn

  • Infective lesions

  • Candidiasis.

  • Syphilitic leukoplakia.

  • Hairy leukoplakia.




  • Immunologically-mediated conditions.

  • Lichen planus.

  • Lupus erythematosus.

  • Geographical tongue.




  • Classification of precancerous lesions:

  • Actinic cheilitis (UV light, lower lip).

  • Idiopathic leukoplakia (unknown).

  • Palatal keratosis associated with reversed smoking.

  • Smokeless tobacco keratosis (snuff).

  • Erythroplakia (unknown).

  • Classification of precancerous conditions:

  • Oral submucous fibrosis.

  • Lichen planus (erosive type).

  • Lupus erythematosus.

  • Candidiasis.

  • Plummer-Vinson syndrome.




  • Syphilitic leukoplakia.

  • Xeroderma pigmentosum.

  • Pachyonychia congenita.

  • Dyskeratosis congenita.

  • Epidermolysis bullosa.




  • Non-epithelial white-yellow lesions.

  • Gingival cysts of infancy.

  • Parulis.

  • Lipoma.

  • Neoplastic lesions

  • Squamous cell carcinoma.

  • Verrucous carcinoma.

  • Classification of white lesions

  • Developmental conditions.

  • Hereditary diseases.

  • Reactive lesions.

  • Infective lesions.

  • Immunologically-mediated conditions.

  • Premalignant lesions & conditions.

  • Non-epithelial white-yellow lesions.

  • Neoplastic lesions.




  • Hereditary benign intraepithelial dyskeratosis

  • An autosomal dominant genodermatosis affecting descendent of a tri-racial isolate.

  • Childhood.

  • Oral and conjuctival mucosa.

  • Oral mucosa: resemble leukoedma or white sponge nevus.

  • Ocular lesions: thick opaque gelatinous plaques on bulbar conjunctiva.




  • Follicular keratosis (Dariers disease)

  • It is an autosomal dominant genodermatosis.

  • Etiology: lack of cohesion among surface epithelia cells.

  • Skin lesions: pruritic papules with accumulation of keratin producing foul odor.

  • painful splitting of nails.

  • Oral lesions: multiple white flat-toped papules in hard palate & alveolar mucosa.



  • Frictional keratosis

  • A white roughened keratotic lesion intervening erosive areas.

  • Etiology: chronic mechanical irritation.

  • Precipitated by psychological condition.

  • Females above 35 years.

  • Types:

  • Linea alba (white line): buccal mucosa bilaterally at the occlusal plane.

  • Chronic cheek, lip or tongue biting.

  • Chronic cheek and tongue biting.




  • Linea alba




  • Nicotine stomatitis

  • A lesion associated with pipe smoking involving hard palate.

  • Males above 45 years.

  • Diffuse gray or white with slightly elevated papules that show punctate red centers.


  • Hypersensitivity to one of the component of toothpaste, usually cinnamon.

  • Slouching and keratosis of oral mucosa.

  • Chewing gum containing cinnamon flavor also may cause this condition.




  • Mucosal aspirin burn

  • Aspirin in small amount induces keratosis but large and for long period cause ulceration.



  • Candidiasis

  • Etiology: Infection with a fungal organism of the Candida species, usually by Candida albicans.

  • Predisposing factors: immunosuppression, diabetes mellitus, antibiotic use, or xerostomia (due to lack of protective effects of saliva).

  • Types: acute pseudomembranous, acute atrophic, chronic atrophic, chronic hyperplastic, mucocutaneous.

  • Chronic hyperplastic candidiasis

  • Pseudomembranous candidiasis




  • Syphilitic leukoplakia:

  • Occurs in tertiary syphilis.



  • Hairy leukoplakia

  • It is Epstein-Barr virus-related lesion in HIV patients.

  • Even in organ transplanted pts.

  • Lateral border of the tongue.

  • White vertical streaks or vertical furrows with shaggy keratotic surface.




  • Lichen planus

  • Immunologically-mediated chronic muco-cutaneous disorder.

  • Etiology: Unknown, autoimmune T cell–mediated disease targeting basal keratinocytes (antigen unknown).

  • Types: reticular, erosive, bullous, atrophic, etc.

  • The reticular form shows lacy white markings ( Wickham striae) on bilatral buccal mucosa.

  • The erosive form shows variable rate of malignant transformation.






  • Erosive form of lichen planus




  • Gingival cyst of infancy




  • Parulis




  • Lipoma




  • Radiation mucositis




  • Squamous cell carcinoma




  • Verrucous carcinoma.




  • Darier’s disease




  • Premalignant lesions & conditions

  • Potentially malignant disorders

  • Definitions:

  • Premalignant lesions:

Morphologically altered tissue that has a greater than normal risk of malignant transformation.

  • Premalignant conditions:

A disease that does not necessarily alter the clinical appearance of local tissue but is associated with a greater than normal risk of precancerous lesion or cancer development in that tissue.



  • Classification of premalignant lesions:

  • Actinic cheilitis (UV light, lower lip).

  • Idiopathic leukoplakia (unknown).

  • Palatal keratosis associated with reversed smoking.

  • Smokeless tobacco keratosis (snuff).

  • Erythroplakia (unknown). (Not white lesion)

  • Histology of premalignant lesions:

  • All they may show variable degree of epithelial dysplasia.

  • Epithelial dysplasia: altered proliferation, maturation, and differentiation of a tissue.

  • Grading of epithelial dysplasia: could be mild, moderate, severe, or carcinoma in situ.

  • Criteria of epithelial dysplasia.



  • Idiopathic leukoplakia




  • Definition:

  • A white patch or plaque that cannot be characterized clinically and pathologically as any other disease.

  • Etiology: the cause is unknown, but certain risk factors have been suggested:

  • Tobacco:

  • Alcohol:

  • UV light.

  • Microorganisms: HPV,T pallidum, Candida

  • Trauma.

  • Nutritional deficiency.

  • Sanguinaria.

  • Clinical features:

  • Diagnosis by exclusion of other white lesions.

  • Epidemiology: global prevalence of 2.6%, increased to 14.6% in those aged 65 yrs.

  • Mean age 60 years.

  • Gender: male.

  • Sites: lip, buccal mucosa, commissure, gum, tongue.

  • High risk sites: tongue, floor of mouth, gums.

  • Clinical presentation:

  • Clinically divided into:

  • Homogenous leukoplakia.

  • Non-homogeneous leukoplakia.

  • Leukoplakia


  • Histopathology:

  • Hyperkeratosis (this gives the white color).

  • Variable degree epithelial dysplasia: mild, moderate, severe, carcinoma in situ, or even early carcinoma.

  • Sub-epithelial chronic inflammatory cell infiltrate.

  • Candida hyphae.

  • Prognosis:

  • 20-45% disappear within 5 years.

  • 17% reduce in size.

  • The rest remains unchanged or increase in size.

  • Malignant transformation rate 0.13% to 17.5% per year.

  • Predictors (markers) of malignant transformation (MT):

  • Age: MT increases with the age (7th decad)

  • Duration: MT increases with the duration.

  • Gender: MT more females.

  • Site: tongue, floor of mouth, gums.

  • Size: MT increases with increases size.

  • Clinical appearance: non-homogeneous.

  • Histopathology: presence and degree of dysplasia.

  • Erythroplakia

  • Erythroplasia of Queyrat

  • Definition

  • A red patch that cannot be clinically or pathologically diagnosed as any other condition.

  • Etiology: similar to oral cancer

  • Tobacco.

  • Alcohol.

  • Nutritional defect.

  • Chronic irritation.

  • Others.

  • Clinical features:

  • Rare.

  • Red area with well-defined margin, soft velvety texture.

  • May associated with leukoplakia (speckled).

  • Older males, 56-75 yrs.

  • Sites: soft palate, mouth floor, buccal mucosa.

  • Erythroplakia


  • Histopathology:

  • Lining epithelium is atrophic and lacking keratin production (gives this red color of mucosa)

  • Sub-epithelial chronic inflammatory cell infiltrate.

  • 40% shows severe/carcinoma in situ.

  • 50% shows invasive carcinoma.

  • Malignant transformation potential 14%-50%.



  • Palatal keratosis associated with reversed smoking




  • Clinical features:

  • Etiology: reversed smoking that produce high temperature combustion products.

  • Certain countries: India, Caribbean & south American.

  • White areas with sometimes ulcerations.

  • Female.

  • Malignant transformation rate 9-15%.

  • Palatal keratosis


  • Actinic cheilitis




  • Clinical features:

  • Etiology: UV light of sunlight.

  • Occupation: outdoor workers.

  • Race: fair skin people.

  • Site: lower lip.

  • Age: above 50 years.

  • Gender: male.




  • Appears as rough, scaly in dry portion, white near wet line of the lip.

  • Finally shows chronic focal ulcerations.

  • Histopathology:

  • Atrophic epithelium with hyperkeratosis.

  • Varying degree of epithelial dysplasia.

  • Sub-epithelial mild inflammatory infiltrate.

  • A band of amorphous acellular basophilic change.

  • Malignant transformation rate 6-10%.




  • Smokeless tobacco keratosis

  • Buccal pouch keratosis

  • Clinical features:

  • Etiology: chewing or dipping ground tobacco leaves.

  • Keratosis (white changes) is common among dippers (60%) more than chewers (15%).

  • Keratosis depends on: habit duration, brand of tobacco, early onset, number of sites, total hours of daily use.




  • It appears as grayish-white, translucent plaque with ill-defined border slight peripheral redness. It is soft velvety with fissured surface (ebb & tide).



  • Histopathology:

  • Hyperkeratosis and acanthosis.

  • Para-keratin chevron.

  • Amorphous esinophilic material in deep lamina properia.

  • Dysplasia is rare.

  • Definition of precancerous conditions:

  • A disease that does not necessarily alter the clinical appearance of local tissue but is associated with a greater than normal risk of precancerous lesion or cancer development in that tissue.

  • Classification of precancerous conditions:

  • Oral submucous fibrosis.

  • Lichen planus (erosive type).

  • Lupus erythematosus.

  • Candidiasis.

  • Plummer-Vinson syndrome.




  • Syphilitic leukoplakia.

  • Xeroderma pigmentosum.

  • Pachyonychia congenita.

  • Dyskeratosis congenita.

  • Epidermolysis bullosa.




  • Oral sub-mucous fibrosis




  • Clinical features:

  • Etiology: alkaloid arecadine found in the areca betel nut. With genetic susceptibility (HLA).

  • Early: vesicles, redness, burning sensation & melanosis.

  • Later: mucosal rigidity & trismus due to progressive fibrosis of the mucosa & the underlying muscles.

  • Malignant transformation rate 7.6%.

  • areca betel nut




  • Oral sub-mucous fibrosis

  • Mucosa is smooth, thin atrophic & pallor with progressive stiffness.

  • Tongue is immobile, small, & atrophic.

  • Sites: buccal mucosa, retromolar, soft palate.




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