Pathology dictionary

What is an epithelial cell?

Epithelial cells are a specialized type of cell that form a thin tissue barrier called an epithelium. This barrier can be on the surface or on the inside of a tissue. There are many different types of epithelial cells found throughout the body.

Types of epithelial cells include:

  • Squamous cells – This type of epithelial cell is found on the surface of the skin and on the inner lining of the mouth, esophagus, and anal canal. Squamous cells are strong cells, capable of handling physical stress.
  • Glandular cells – This type of epithelial cell is found in organs throughout our body including the stomach, colon, breast, and prostate. Glandular epithelial cells often form round structures called glands that make different types of substances.
  • Urothelial – This type of epithelial cell is found on the inner surface of the bladder. Urothelial cells form a protective barrier on the inside of the bladder. They are also specially designed to stretch as the bladder fills with urine.
Cancer that start from epithelial cells

Many different types of cancer can start from epithelial cells. All cancers in this group are called carcinomas. These cancers can start in any area of the body where epithelial cells are normally found.

Types of cancer that start from the cells in the epithelium include:

Non-invasive cancers and pre-cancerous conditions

Sometimes the abnormal epithelial cells are seen only inside the epithelium, Pathologists call this condition dysplasia. Carcinoma in situ is a diagnosis pathologists use to describe epithelial cells that look the same as cancer cells but are still seen only in the epithelium. Carcinoma in situ is called a non-invasive type of cancer because the abnormal epithelial cells have not spread to the tissue below the epithelium. The movement of abnormal epithelial cells out of the epithelium and into the tissue below is called invasion.

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