Squamous Cells: Definition

Squamous cells are flat, thin cells that form protective surfaces on both the outside and inside of the body. Their shape resembles small plates or scales, allowing them to pack tightly together and create a strong barrier. This barrier protects the tissues underneath from injury, infection, and environmental exposure.

These cells are part of a group called epithelial cells, which line and cover many organs. Because squamous cells are found in so many places, they play an essential role in maintaining the health and function of multiple body systems.

Where are squamous cells normally found?

Squamous cells form the outermost layer of the skin, where they defend the body against sunlight, chemicals, germs, and physical injury. They also line many internal surfaces that come into contact with the outside environment or experience frequent friction. Examples include the mouth, throat, esophagus, lungs, cervix, anus, and vagina.

These locations all require a durable, renewable layer of protection, and squamous cells are well-suited for this task.

What do squamous cells do?

The main job of squamous cells is to act as a protective shield. On the skin, they keep harmful bacteria, viruses, and chemicals from entering the body. Inside organs, they protect delicate tissue from friction, irritation, and infection.

Squamous cells are constantly renewing themselves. Older or damaged cells naturally shed and are replaced by new ones. This continuous turnover helps maintain a healthy barrier and allows the body to repair everyday wear and tear.

What types of cancer arise from squamous cells?

A cancer that starts from squamous cells is called a squamous cell carcinoma. Because squamous cells are widespread, this type of cancer can develop in many organs.

Squamous cell carcinoma most often affects the skin, especially in areas exposed to the sun. It can also arise inside the body, including the mouth, throat, lungs, cervix, vagina, and anus.

The behaviour of squamous cell carcinoma varies depending on the location. Some tumours grow slowly and remain localized, while others may proliferate or spread to lymph nodes and other organs. Early detection and treatment greatly improve outcomes.

What do squamous cells look like under the microscope?

When examined under the microscope, healthy squamous cells appear flat and thin with a central nucleus and a small amount of clear cytoplasm. They are arranged in orderly layers, which gives the tissue a smooth, uniform surface.

In contrast, cancerous squamous cells look very different. In squamous cell carcinoma, the cells may appear larger, irregularly shaped, darker, or more crowded than normal. They may lose their organized layering and instead grow in disorganized groups or nests. These changes help pathologists recognize cancer and determine its aggressiveness.

Questions to ask your doctor

• Why were squamous cells mentioned in my pathology report?

• Were the squamous cells normal or abnormal?

• If abnormal, do the findings suggest squamous cell carcinoma or a precancerous change?

• What treatment or follow-up is recommended based on these results?