Masthan M. K, E. Rajesh E, Tamilarasi U, Anitha N. Grading of Oral Epithelial Dysplasia – A Review. Biomed Pharmacol J 2016;9(2).
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Grading of Oral Epithelial Dysplasia – A Review

M. K. Masthan, E. Rajesh, U. Tamilarasi and N. Anitha

Department of Oral Pathology, Sree Balaji Dental College and Hospital, Bharath University, Pallikaranai, Chennai-600100.



Pathologist  assess oral precancerous lesions with their  dysplastic features  by grading of oral epithelial dysplasia (OED) .Evaluating of precancerous lesion arises from two factors (1) lack of knowledge in  predicting future development of cancer. (2) Lack of  evaluating the criteria which is already established.  This article  provide a detail review of all the grading systems.


epithelial dysplasia; precancerous; photographic

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Oral squamous cell carcinoma is a most common changes in the oral mucosa1. leukoplakia is one of the most common potentially malignant disorders2. Dysplasia is reversible. When the stimulus is removed , the dysplastic changes will revert back to normal. When the irritant is removed , epithelium shows cellular atrophy3. It manifest as a cell death or neoplastic transformation. In epithelial dysplasia malignant development is more important than the clinical characteristics2,4.

Grading in dysplasia 

Many combinations of dysplastic features are used in grading system and there is difficulty in assessing the various degrees of epithelial dysplasia . To assess the severity of the dysplastic features many grading systems have been proposed . There are various grading systems given by many authors , following are the most commonly used grading systems

Smith and Pindborg’s classification5

1978 WHO classification6

Ljubljana classification squamous intraepithelial lesions (SIL)7,8

2005 WHO classification9

New Binary system10

Smith and Pindborg Classification5

In the year 1969 Smith and Pindborg  were first  to standardize the grading  for epithelial dysplasia  . This system was based on the means of the different histological changes and  photographic method. In this method standardized photographs are being compared with histologic sections and given 13 histologic features. Now they graded the epithelial dysplasia as absent , marked or slightly and also the score is given. For absent the score was given as zero and for marked or slightly the score was between 1 and 10

1978 WHO Classifi cation6

The “histopathological typing of cancer and precancer lesions ” was given by WHO in the year 1997 . They have given 12 characteristics of the epithelial dysplasia which was graded as mild , moderate and severe according to the characters which are present.

List of Characteristic  features are

Loss of polarity of basal cells

An increased nuclear-cytoplasmic ratio

Drop shaped rete pegs

The presence of more than one layer of cells havingthe basaloid appearance

Increased number of mitotic figures

Irregular epithelial stratification

The presence of mitotic figures in the superficial halfof the epithelium

Nuclear hyperchromatism

Cellular polymorphism

Reduction of cellular cohesion

Enlarged nucleoli

Keratinization of single cells or cell groups in the

prickle cell layer

They graded epithelial dysplasia as




Mild dysplasia

Nuclear abnormality is slight in the basal third of epithelium  and it was minimal in the upper layer with cell maturation. Few abnormal mitosis maybe seen accompanied by chronic inflammation.

Moderate dysplasia

Basal 2/3rd of the epithelium shows  nuclear abnormalities persisting up to thesurface. Cell maturation and stratification are seen in the upper layer. Mitosis occurs in the Parabasal and intermediate layer.

Severe dysplasia

More than 2/3rd of the epithelium shows  nuclearabnormalities and cell maturation is lost. stratification and abnormal mitosis  is seen in the superficial layers. Carcinoma in situ was mergedinto severe dysplasia.

Ljubljana Classifi cation SIL

In the  year 2003 zeodner proposed criteria for grading hyperplastic epithelial lesions of the oral cavity as simple , atypical and abnormal hyperplasia

Simple hyperplasia

Basal and parabasal layer remains intact without any cellular atypia and thickening of the prickle cell layer is seen.

Abnormal hyperplasia

It shows increase in size from basal layer up to halfof the epithelial thickness. Stratification remains unchanged with moderately enlarged nuclei. Basal cell layer shows mitosis and dyskeratosis is seen less than 5% of the epithelial cells

Atypical hyperplasia (risky epithelium)

Cells of the epithelium  are altered showing malignant changes but it is not to form carcinomatous cells . Epithelial stratification remains unchanged and nuclei is enlarged with irregular contour. Mitotic figures is increased upto to the  2/3rd of the epithelium with increasednuclear-cytoplasmic ratio. Civatte bodies and  Dyskeratotic cells may be present.

Carcinoma in situ

Stratification is completely lost and mitotic figures are seen all over the epithelium7

2005 WHO Classifi cation9

In the year 2003 WHO classified the oral epithelial dysplasia as  Mild, moderate,severe, carcinoma in situ or hyperplasia based on the  architectural changes and the presence or severity of cellular atypia according tothe presence and severity of cellular atypia and thearchitectural features. It was issued by WHO in the new book  “classification of tumors of the head andneck.”9

Architectural characteristics

Abnormally superficial mitoses

Irregular epithelial stratification

Drop-shaped rete ridges

Keratin pearls within rete pegs

Loss of polarity of basal cells

Increased number of mitotic figures

Cellular characteristics

Anisonucleosis and Anisocytosis

Nuclear and Cellular pleomorphism


Increased number and size of nucleoli

Increased nuclear-cytoplasmic ratio

Atypical mitotic figures

Grading systems of oral epithelial dysplasia

Mild dysplasia

Architectural changes limited only tothe lower third of the epithelium along with the cytological atypia

Moderate dysplasia

Architectural changes is seen extending tothe middle third of the epithelium. Degree of cytologicatypia requires upgradation

Severe dysplasia

Architectural disturbances is seen Greater than 2/3rd of the epithelium and the increasednumber of the cytologic atypia

Carcinoma in situ

Architectural disturbances are seen throughout the full thickness of the epithelium. Abnormal mitosis is seen on the superficial layer with atypical figures


Histopathological assessed severity of oral epithelial dysplasia remains the gold standard for the prediction of malignant transformation of precancerous lesions


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