Keratinizing squamous dysplasia of the oral cavity

by Jason Wasserman MD PhD FRCPC
March 30, 2023

What is keratinizing squamous dysplasia in the oral cavity?

Keratinizing squamous dysplasia is a pre-cancerous disease that starts from specialized squamous cells that cover the inside surface of the oral cavity. This area includes the lips, tongue, floor of mouth, cheeks, and hard palate. Keratinizing squamous dysplasia is considered a pre-cancerous disease because it can over time turn into a type of cancer called squamous cell carcinoma.

Is keratinizing squamous dysplasia cancer?

No. Keratinizing squamous dysplasia in the oral cavity is not cancer. It is, however, a precancerous condition that can turn into a type of cancer called squamous cell carcinoma over time.

What causes keratinizing squamous dysplasia in the oral cavity?

The most common cause of keratinizing 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 keratinizing squamous dysplasia made?

The diagnosis of keratinizing squamous dysplasia 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 it mean if keratinizing squamous dysplasia is described as mild, moderate, or severe?

In the oral cavity, keratinizing squamous dysplasia is commonly divided into three grades: mild keratinizing squamous dysplasia, moderate keratinizing squamous dysplasia, and severe keratinizing squamous dysplasia.

The grade of keratinizing squamous dysplasia is very important because it is related to the risk of developing a type of cancer called squamous cell carcinoma in the future. Mild keratinizing squamous dysplasia is associated with the lowest risk of developing cancer and those who do develop cancer tend to develop it after many years. Moderate and severe keratinizing squamous dysplasia are associated with the highest risk of developing cancer and patients are typically offered treatment to remove the disease before it progresses to cancer.

Pathologists determine the grade by comparing the abnormal cells in the disease area to the healthy squamous cells normally found in the oral cavity. Specifically, pathologists look at the size, shape, and colour of the abnormal squamous cells and the number of mitotic figures (dividing cells).

What is a margin and why are margins important?

A margin is any tissue that was cut by the surgeon in order to remove the abnormal area of tissue 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 are usually only 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 dysplasia is seen at the very edge of the cut tissue. A positive margin is associated with a higher risk that dysplasia will come back at the same site after treatment.