Squamous cell carcinoma in situ of the larynx

by Jason Wasserman MD PhD FRCPC and Zuzanna Gorski MD
December 30, 2023

Squamous cell carcinoma in situ of the larynx is a non-invasive type of cancer. If left untreated, this condition can evolve into a type of invasive laryngeal cancer called squamous cell carcinoma. This condition typically affects adults over the age of 40 years.

The larynx

The larynx is a structure located in the upper neck just above the trachea. Its functions include protecting the airway and sound production. It is divided into three parts: the supraglottis, glottis, and subglottis. The glottis which includes the vocal cords is the most common location for squamous cell carcinoma in situ. However, as the tumour grows it can spread to other parts of the larynx. This is called transglottic extension.

anatomy head and neck

What causes squamous cell carcinoma in situ in the larynx?

The most common cause of squamous cell carcinoma in situ in the larynx is smoking. Other causes include excessive alcohol consumption, immune suppression, and prior radiation to the neck.

What are the symptoms of squamous cell carcinoma in situ of the larynx?

Symptoms of squamous cell carcinoma in situ of the larynx include breathing problems, hoarseness or voice changes, and difficulty swallowing.

Squamous cell carcinoma in situ of the larynx

In squamous cell carcinoma in situ, abnormal squamous cells replace the normal healthy squamous cells in the epithelium, a thin layer of tissue on the inside surface of the larynx. When examined under the microscope, the abnormal squamous cells are typically larger and hyperchromatic (darker) than the normal healthy squamous cells. An abnormal pattern of maturation called keratinization may also be seen. Cells that show keratinization contain large amounts of a protein called keratin which is abnormal in the larynx.

Squamous cell carcinoma in situ in the larynx is considered a non-invasive disease because the abnormal cells are confined to the epithelium. In contrast, squamous cell carcinoma is considered an invasive disease because the abnormal squamous cells have spread into the underlying stroma.

Squamous cell carcinoma in situ


In pathology, a margin refers to the edge of tissue removed during tumour surgery. The margin status in a pathology report is important as it indicates whether the entire tumour was removed or if some was left behind. This information helps determine the need for further treatment.

Pathologists typically assess margins following a surgical procedure like an excision or resection, aimed at removing the entire tumour. Margins aren’t usually evaluated after a biopsy, which removes only part of the tumour. The number of margins reported and their size—how much normal tissue is between the tumour and the cut edge—vary based on the tissue type and tumour location.

Pathologists examine margins to check if tumour cells are present at the tissue’s cut edge. A positive margin, where tumour cells are found, suggests that some cancer may remain in the body. In contrast, a negative margin, with no tumour cells at the edge, suggests the tumour was fully removed. Some reports also measure the distance between the nearest tumour cells and the margin, even if all margins are negative.



Other helpful resources

Atlas of Pathology
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