Squamous Metaplasia

What is squamous metaplasia?

Squamous metaplasia refers to noncancerous (benign) changes in squamous cells in your epithelium. The epithelium is a thin tissue that lines glands and organs, including your skin.

Squamous cells exist throughout your body. In rare instances, squamous metaplasia can become cancerous (malignant).

What does squamous metaplasia mean?

It may be easier to understand this condition when you break down its meaning:

• Squamous (SKWAY-mess) refers to the small, scale-like cells that make up your epithelium.
• Metaplasia (meh-tuh-PLAY-zhuh) refers to cells that change into a different type of cell. This new cell type isn’t usually found in the tissue where it develops.

What are the types of squamous metaplasia?

Healthcare providers classify squamous metaplasia by how these cells change. Squamous metaplasia may be:

• Keratinizing (leukoplakia): In this type, your cells make too much keratin (a protein) as they move from one epithelial layer to the next. In healthy squamous cells, this protein helps form tissue, hair, skin and nails. Keratin also makes up the lining of organs and glands.
• Nonkeratinizing: Your cells don’t accumulate large amounts of protein (keratinization).

Is squamous metaplasia precancerous?

Nonkeratinizing squamous metaplasia is a noncancerous condition. It won’t become cancerous.

Keratinizing squamous metaplasia may be precancerous. This means the condition may develop into cancer if not treated.

What happens if squamous metaplasia becomes cancer?

Untreated keratinizing squamous metaplasia first turns into dysplasia. Dysplasia means there’s an increase in abnormal cells in tissues or organs.

If left untreated, dysplasia can become neoplasia. Irregular cells grow uncontrollably, forming a neoplasm or tumor. A tumor may be cancerous or noncancerous.

When squamous cells become cancerous, squamous cell carcinoma occurs. You may be familiar with squamous cell carcinoma as a type of skin cancer. But the cutaneous (skin) form is only one type. Squamous cells are also in the mucous membranes that line your mouth, nose, airways and cervix.

What is cervical squamous metaplasia?

Squamous metaplasia can affect any part of your epithelium. It most commonly develops in the mucus-making cells that line your endocervix, a part of the female reproductive system. This passageway inside your cervix connects your uterus and vagina.

Nonkeratinizing cervical squamous metaplasia is common in women and people assigned female at birth, and is considered a normal difference. More than 8 in 10 people of childbearing age have it, as do 3 in 4 people in menopause. This common cell change doesn’t increase cancer risk.

Some people who have human papillomavirus (HPV) develop precancerous cervical squamous metaplasia. HPV is the most common sexually transmitted disease (STD). Cervical squamous metaplasia may develop into cervical dysplasia (cervical intraepithelial neoplasia). Left untreated, these cell changes can cause cervical cancer.

Where else does squamous metaplasia develop?

Squamous metaplasia may also develop in your:

• Bladder and urinary system.
• Digestive system.
• Mouth, tongue and tonsils.
• Respiratory system.
• Skin.

What causes squamous metaplasia?

Experts don’t know why some cells change, causing squamous metaplasia. These factors may increase your risk for developing certain types:

• Hormone therapy and radiation therapy to treat prostate cancer can cause squamous metaplasia in your urethra. This tube carries pee (urine) from your bladder out of your body.
• HPV can lead to cervical squamous metaplasia.
• Longstanding urinary catheterization and frequent urinary tract infections (UTIs) or kidney stones can cause bladder squamous metaplasia.
• Smoking and chronic obstructive pulmonary disease (COPD) increase your risk of bronchial squamous metaplasia.
• Vitamin A deficiency can cause squamous metaplasia in your airways.

What are the symptoms of squamous metaplasia?

Symptoms of squamous metaplasia vary depending on the affected area. Many people have no noticeable signs.

People with bladder squamous metaplasia may experience urge incontinence (an urgent need to pee).

Cervical squamous metaplasia may cause cervicitis. This inflammation of your cervix doesn’t always cause symptoms. When symptoms occur, they include:

• Foul-smelling vaginal discharge or irritation.
• Painful sex (dyspareunia).

How is squamous metaplasia diagnosed?

Testing for squamous metaplasia varies depending on the affected area. Healthcare providers screen for cervical cancers using Pap smears to check for changes to cervical and endocervical cells and HPV tests to detect if you’ve had prior exposure. If the test results indicate risk for precancerous changes, you may be referred for a colposcopy to examine cervical tissue cells.

For other types of squamous metaplasia, your provider may perform a biopsy to remove cells from the affected area. A specialist (pathologist) examines these cells under a microscope for signs of cell changes or disease.

How is squamous metaplasia treated?

Nonkeratinizing squamous metaplasia rarely needs treatment. But keratinizing squamous metaplasia can increase cancer risk.

Your healthcare provider will conduct regular tests to check for signs of cancer. If cell changes indicate a problem, your provider will select the best treatment based on the affected body area.

What should I ask my provider?

You may want to ask your healthcare provider:

• What caused the squamous metaplasia?
• Am I at risk for cancer? How can I lower this risk?
• Do I need treatment?
• How often should I get screenings?
• Should I look out for signs of complications?

A note from Cleveland Clinic

Squamous metaplasia is a noncancerous change in the cells that make up the tissue lining for organs and glands (epithelium). Most people have nonkeratinizing cervical squamous metaplasia. This condition doesn’t increase cancer risk. Keratinizing squamous metaplasia can turn into dysplasia, which may lead to cancer. Your healthcare provider will perform ongoing tests to check for changes in cells that may indicate cancer.