In pathology, poorly differentiated is a term used to describe how cancer cells look under a microscope. When cells are poorly differentiated, they appear very different from normal cells in the body. Normal cells are well-organized and have specific structures, but poorly differentiated cells lose these typical features, making it hard to tell where they came from. This lack of resemblance to normal cells can affect how the tumour behaves and how it may respond to treatment.
Yes, poorly differentiated tumours are often considered aggressive. Because the cells look so different from normal cells, they tend to grow and spread more quickly than well differentiated tumours, which look more like normal cells. This increased growth rate can make poorly differentiated tumours more challenging to treat, as they may spread to other body parts faster.
Poorly differentiated tumours can start in many different tissues throughout the body. They often originate in epithelial cells, which line the surfaces of organs and tissues, such as the skin, lungs, and digestive tract. Because poorly differentiated cells lose many features that link them to a specific tissue, it can sometimes be challenging for pathologists to determine exactly where the tumour started. Special tests such as immunohistochemistry (IHC) may be needed to identify the tissue of origin.
In many types of cancer, treatment is guided by the grade of the tumour, which describes how much the cancer cells resemble normal cells. Grade is based on the degree of differentiation, with tumours generally categorized as well differentiated, moderately differentiated, or poorly differentiated.
Poorly differentiated tumours are assigned a higher grade because they are more likely to grow quickly and spread to other body parts. Knowing the grade helps doctors choose the most appropriate treatment.
Poorly differentiated is a descriptive term rather than a stage. The stage of a tumour refers to how advanced it is and is based on the tumour’s size, location, and whether it has spread to nearby lymph nodes or other organs. Poorly differentiated tumours can be found at any stage, from an early, localized stage to an advanced stage, with spread to other parts of the body.
In summary, while “poorly differentiated” describes how the cancer cells look and behave, the tumour stage provides information about the extent of the cancer. Both the grade and stage are important for guiding treatment and understanding the tumour’s behaviour.
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.