by Jason Wasserman, MD PhD FRCPC, reviewed on March 6, 2020
This article will help you read and understand your pathology report for squamous dysplasia in the oral cavity. Go here to learn more about squamous dysplasia in other parts of the body.
The oral cavity is the beginning of the aerodigestive tract. It is used for both breathing and taking in food. The oral cavity is a complex area of the body that is made up of many parts.
The oral cavity includes:
The inner surface of the oral cavity is covered by cells called squamous cells. that form a barrier called the epithelium. The tissue below the epithelium is called stroma. Pathologists use the word mucosa to describe tissue that includes both the epithelium and the stroma.
Squamous dysplasia in the oral cavity is a pre-cancerous disease. It is called pre-cancerous because it can over time turn into a type of cancer called squamous cell carcinoma. Squamous dysplasia can start in any part of the oral cavity although the most common location is the lateral border of the tongue.
The risk associated with squamous dysplasia turning into cancer depends on how abnormal the squamous cells look under the microscope. The risk of cancer is highest when your pathologist describes the changes as severe (see Grade below).
The most common cause of squamous dysplasia in the oral cavity is smoking. Other causes include excessive alcohol consumption, immune suppression, and prior irradiation. Smoking in particular causes the squamous cells to undergo an abnormal pattern of development which results in a process called keratinization. Because of this, some pathology reports will describe this condition as “keratinizing squamous dysplasia”.
The diagnosis of squamous dysplasia can only be made after a tissue sample is examined under the microscope. Compared to normal, healthy squamous cells, the abnormal cells in an area of squamous dysplasia are larger, darker, and disorganized. Pathologists use the word hyperchromatic to describe cells that look darker than normal cells. Large clumps of genetic material called nucleoli may also be seen in the nucleus of the abnormal cells.
The abnormal cells in squamous dysplasia are only seen in the epithelium. This is different from squamous cell carcinoma where the abnormal cells are also seen in the stroma below the epithelium. The movement of abnormal cells from the epithelium into the stroma is called invasion. Your pathologist will carefully examine your tissue sample to make sure there is no evidence of invasion before making the diagnosis of squamous dysplasia.
The diagnosis of 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.
Depending on the grade of the disease (see Grade below), your doctor may recommend surgery to remove all of the abnormal tissue or close clinical follow-up.
Pathologists use the size, colour, and shape of the cell to determine the grade. Using these features, dysplasia in the oral cavity is usually divided into three levels:
Some pathology reports will group moderate and severe dysplasia together and call them both high grade dysplasia. Mild dysplasia is called low grade dysplasia.
Why is this important? The grade is very important because it is related to the risk of developing an invasive cancer in the future. Mild (low grade) dysplasia has a very 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 becoming cancer and patients with this condition are usually offered treatment to remove the diseased tissue.
A margin is any tissue that was cut by the surgeon in order to remove the abnormal tissue from your body. Whenever possible, surgeons will try to cut tissue outside of the abnormal area to reduce the risk that any abnormal cells will be left behind after the tissue is removed.
Your pathologist will carefully examine all the margins in your tissue sample to see how close the abnormal cells are to the edge of the cut tissue.
A margin is called positive when there are abnormal cells at the very edge of the cut tissue.
A negative margin means there were no abnormal cells at the very edge of the cut tissue. If all the margins are negative, most pathology reports will say how far the closest abnormal cells were to a margin. The distance is usually described in millimeters.
Margins will only be described in your report after the entire area of abnormal tissue has been removed.
Why is this important? A positive margin is associated with a higher risk that the disease will come back in the same site after treatment. Most pathologists only consider moderate or severe dysplasia (high grade dysplasia) at the cut edge of the tissue to be a positive margin.