June 22, 2023


In pathology, the term atypia is used to describe cells that look abnormal when examined under the microscope. These changes can affect the cytoplasm (body) of the cell or the nucleus (the part of the cell that holds the genetic material).

Does atypia mean cancer?

Atypia does not necessarily mean that the cells are cancerous. Although atypia is commonly seen in malignant (cancerous) tumours, this change can be seen in a variety of benign (non-cancerous) conditions. Your pathologist will use this information in combination with the results of other tests to make a final diagnosis.

What causes a cell to show atypia?

There are many reasons why cells may show atypia. Common causes include:

  • Inflammation – Inflammation is the body’s natural defense against injury or disease.  The body also uses inflammation to repair tissue after an injury has taken place. The cells that take part in inflammation are called inflammatory cells and they are part of the body’s immune system. Normal, healthy cells can show atypia when they are close to inflammatory cells. In this situation, this change goes away when the inflammation stops.
  • Infection – Cells that become infected by a virus can show marked atypia. Pathologists sometimes call this type of atypia viral cytopathic effects. The abnormal cells will go away once the infection is removed from the body.
  • Radiation – Radiation is a common treatment for cancer. Normal, healthy cells that have been exposed to radiation commonly look marked atypia when examined under the microscope. Your doctor should always let your pathologist know if you are receiving currently radiation or have received radiation in the past.
  • Precancerous diseases – Most precancerous conditions show atypia when examined under the microscope. Precancerous diseases that show this change include dysplasia and carcinoma in situ.
  • Cancer – Almost all cancers will show some degree of atypia when examined under the microscope. In this case, this change is very important because it helps your pathologist make the diagnosis and determine the tumour grade.

It is important to remember that atypia is a description of the way the cells look under the microscope and not a complete diagnosis by itself. In many cases, your pathologist will try to determine the cause of this change. If the cause is known, it will be described in your pathology report. However, your doctors may only be able to determine the cause later with the help of additional information about you and your medical history.

About this article

This article was written by doctors to help you read and understand your pathology report. Contact us if you have questions about this article or your pathology report. For a complete introduction to your pathology report, read this article.

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