Pathology dictionary -


Reactive is a word pathologists use in two different situations. In the first situation, reactive is used to describe cells that look abnormal when examined under the microscope but are not cancer cells. In the second situation, reactive is used to describe the results of a special test such as immunohistochemistry

1 . Cell that look abnormal when examined under the microscope.

Reactive cells look abnormal. They are called reactive because their abnormal look is caused by something close to the cells. Put another way, the cells are reacting to something around them. Reactive cells are not cancer cells.


Cells can develop a reactive look for many reasons including infection, inflammation, physical stress, and radiation. For example, the cells that line the inside of the stomach may look reactive if the stomach is infected by bacteria (usually a species called H. pylori). Similarly, the cells that line the inside of the esophagus will appear reactive in people who suffer from acid reflux disease.


Reactive is not a diagnosis. Rather it is used to described the cells seen under the microscope. The diagnosis used will depend on where the reactive change is seen (the location in the body) and why it is happening.

2. Results of a special test.

In the second situation, pathologists use the word reactive to describe the results of a special test. The most common test described in this way is called immunohistochemistry. Pathologists often describe cells or tissues that show a positive result as reactive while those that show a negative result as non-reactive. 

  • Facebook
  • Twitter

Copyright 2017

For more information about this site, contact us at

Disclaimer: The articles on MyPathologyReport are intended for general informational purposes only and they do not address individual circumstances. The articles on this site are not a substitute for professional medical advice, diagnosis or treatment and should not be relied on to make decisions about your health. Never ignore professional medical advice in seeking treatment because of something you have read on the MyPathologyReport site. The articles on are intended for use within Canada by residents of Canada only.

Droits d'auteur 2017
Pour plus d'informations sur ce site, contactez-nous à
Clause de non-responsabilité: Les articles sur MyPathologyReport ne sont destinés qu’à des fins d'information et ne tiennent pas compte des circonstances individuelles. Les articles sur ce site ne remplacent pas les avis médicaux professionnels, diagnostics ou traitements et ne doivent pas être pris en compte pour la prise de décisions concernant votre santé. Ne négligez jamais les conseils d'un professionnel de la santé à cause de quelque chose que vous avez lu sur le site de MyPathologyReport. Les articles sur sont destinés à être utilisés au Canada, par les résidents du Canada uniquement.