Atypia

In pathology, the term atypia describes 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 malignant?

Atypia does not necessarily mean malignant (cancerous). While malignant tumors commonly contain cells with atypia, these changes can also occur in many non-cancerous conditions. Your pathologist will consider these findings alongside other test results and your medical history to determine the exact significance of atypia in your case.

Does atypia mean benign?

Cells with atypia can indeed be part of benign (non-cancerous) conditions. However, atypia is also frequently seen in precancerous or cancerous conditions. Because of this, your doctor may recommend additional tests or regular monitoring to better understand the significance of the atypia.

What causes 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. The cells that take part in inflammation are called inflammatory cells and are part of the body’s immune system. Normal, healthy cells can show atypia when 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 exposed to radiation commonly look marked atypia when examined under the microscope. Your doctor should always let your pathologist know if you are currently receiving 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 tumor grade.

It is important to remember that atypia describes how the cells look under the microscope. It is not a complete diagnosis. Your pathologist will often try to determine the cause of this change. If the cause is known, it will be described in your pathology report. However, your doctor may only be able to determine the cause later with the help of additional information about you and your medical history.

What does atypia look like under the microscope?

Under the microscope, cells with atypia often have irregular shapes, sizes, or structures. Their nuclei may appear enlarged or abnormally shaped, and the genetic material within the nuclei may look different from normal. The cell boundaries might be unclear, and cells can vary greatly from the healthy cells around them. These microscopic details allow pathologists to detect atypia and investigate further to identify the underlying cause.

About this article

Doctors wrote this article 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.