Squamous cell carcinoma (SCC)

Squamous cell carcinoma is a type of cancer that starts from squamous cells, which are flat, thin cells found on the surface of the skin and lining many internal body parts, such as the mouth, throat, lungs, and cervix. It occurs when these squamous cells grow uncontrollably, forming a malignant (cancerous) tumor that can invade nearby tissues and potentially spread to other body parts.

What are the symptoms of squamous cell carcinoma?

Symptoms depend on where the cancer develops. On the skin, squamous cell carcinoma often appears as a firm, red bump, a scaly patch, or a sore that doesn’t heal. When located inside the mouth or throat, symptoms can include persistent soreness, difficulty swallowing, or changes in voice. If it develops in the lungs, symptoms may include coughing, shortness of breath, or chest pain. Some patients may not notice symptoms until the cancer has grown larger or spread.

What causes squamous cell carcinoma?

Squamous cell carcinoma is commonly caused by damage to the DNA of squamous cells. Major risk factors include chronic sun exposure (for skin cancer), smoking and alcohol use (for cancers of the mouth, throat, and lungs), human papillomavirus (HPV) infection (especially for cancers in the throat, cervix, anus, and genitals), and chronic irritation or inflammation of the affected area.

What parts of the body can be affected by squamous cell carcinoma?

Squamous cell carcinoma can develop wherever squamous cells are present. Common sites include:

• Skin (especially sun-exposed areas such as the face, ears, and hands)

• Mouth and throat (oral cavity, tonsils, base of tongue)

• Lungs and airways

• Cervix, vagina, anus, and penis

What does metastatic squamous cell carcinoma mean?

Metastatic squamous cell carcinoma means the cancer has spread from its original location to other areas of the body. Cancer cells typically spread through lymph vessels or the bloodstream, forming new tumors (metastases) in lymph nodes or distant organs such as the lungs, liver, or bones. Metastatic cancer is usually more challenging to treat and can significantly affect a patient’s prognosis.

How is this diagnosis made?

The diagnosis of squamous cell carcinoma usually involves a biopsy, a procedure in which a pathologist examines a small tissue sample from the suspicious area under a microscope. Additional tests, such as imaging (CT, MRI, or PET scans) or special lab tests (such as immunohistochemistry), may also be performed to confirm the diagnosis, determine the extent of disease, and help plan treatment.

What does squamous cell carcinoma look like under the microscope?

Under the microscope, squamous cell carcinoma shows abnormal squamous cells arranged in irregular patterns. Cancerous squamous cells often have enlarged, irregular nuclei (the part of the cell containing DNA), visible mitotic figures (indicating active cell division), and may form clusters or groups, invading deeper tissue layers. Pathologists look carefully at these features to confirm the diagnosis and determine how aggressive the tumor is.

How do pathologists grade squamous cell carcinoma?

Pathologists grade squamous cell carcinoma based on how much the cancer cells resemble normal squamous cells. Tumors are typically classified as:

• Well-differentiated: Cancer cells closely resemble normal squamous cells, tend to grow more slowly, and often behave less aggressively.

• Moderately differentiated: Cells look somewhat abnormal and tend to grow and spread at an intermediate rate.

• Poorly differentiated: Cells look very abnormal, grow quickly, and are usually more aggressive, with a higher likelihood of spreading to other body parts.

Grading helps doctors predict the tumor’s behavior and guides the best treatment plan for the patient.