Squamous dysplasia of the oral cavity

by Jason Wasserman MD PhD FRCPC
June 16, 2022

About this article: This article was created by doctors to help you read and understand your pathology report for squamous dysplasia of the oral cavity. If you have any questions about this article or your pathology report, please contact us.

What is squamous dysplasia in the oral cavity?

Squamous dysplasia in the oral cavity is a pre-cancerous disease. It develops from the squamous cells that cover the inside surface of the oral cavity which includes the tongue, gingiva (gums), buccal mucosa (inner cheeks), floor of mouth, and palate (roof of the mouth). If left untreated, squamous dysplasia can progress over time into a type of cancer called squamous cell carcinoma. Pathologists divide squamous dysplasia into three levels – mild, moderate, and severe – and the risk for developing cancer is highest with severe squamous dysplasia.

What causes squamous dysplasia in the oral cavity?

The most common cause of squamous dysplasia in the oral cavity is smoking. Other causes include excessive alcohol consumption, immune suppression, and inflammatory conditions such as lichen planus.

How is the diagnosis of squamous dysplasia in the oral cavity made?

The diagnosis of squamous dysplasia in the oral cavity is usually made after a small sample of tissue is removed in a procedure called a biopsy. The biopsy is usually performed because you or your doctor saw an abnormal-looking area of tissue within your oral cavity. Your pathology report will probably say what part of the oral cavity was sampled in the biopsy. The diagnosis can also be made after a larger piece of tissue is removed in a procedure called an excision.

What does squamous dysplasia look like under the microscope?

When examined under the microscope, the abnormal cells in an area of squamous dysplasia are usually larger than normal, healthy squamous cells. The cells may be described as hyperchromatic as the nucleus (the part of the cell that holds the genetic material) is often darker than normal. Large clumps of genetic material called nucleoli may also be seen in the nucleus of the abnormal cells. These squamous cells also undergo an abnormal pattern of development which results in a process called keratinization.

squamous dysplasia oral cavity

How do pathologists grade squamous dysplasia in the oral cavity?

Pathologists divide squamous dysplasia in the oral cavity into three levels called mild, moderate, and severe. Pathologists determine the level by comparing the abnormal squamous cells to normal, healthy squamous cells in the oral cavity. Another name for mild squamous dysplasia is low-grade dysplasia while moderate and severe keratinizing squamous dysplasia are grouped together and called high-grade dysplasia.

The level or grade of dysplasia in the oral cavity is very important because it is related to the risk of developing cancer in the future. Mild (low-grade) dysplasia has a low risk of turning into cancer and is often left untreated. Moderate and severe (high-grade) dysplasia is associated with a much higher risk of progressing to cancer and patients with this condition are usually offered treatment to remove the diseased tissue.

What is a margin?

A margin is any tissue that was cut by the surgeon in order to remove the area of squamous dysplasia from your body. The types of margins described in your report will depend on the area of the oral cavity involved and the type of surgery performed. Margins will only be described in your report after the entire abnormal area of tissue has been removed.

A negative margin means that dysplasia was not seen at any of the cut edges of tissue. A margin is called positive when there is moderate or severe squamous dysplasia at the very edge of the cut tissue. A positive margin is associated with a higher risk that squamous dysplasia will come back at the same site after treatment.


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