by Jason Wasserman MD PhD FRCPC
April 25, 2023
Squamous dysplasia (also called epithelial dysplasia) is a precancerous 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. Squamous dysplasia is considered a pre-cancerous disease because it can over time turn into a type of cancer called squamous cell carcinoma.
No. 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.
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.
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.
In the oral cavity, squamous dysplasia is commonly divided into three grades: mild squamous dysplasia, moderate squamous dysplasia, and severe squamous dysplasia.
The grade of 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 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 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).
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.