December 5, 2023

In pathology, the term “differentiated” refers to the degree of specialization and maturity of cells within a tissue or organ. Differentiation is the process by which cells acquire specific structures and functions that enable them to perform particular roles within the body.

What does differentiated mean when describing a tumor?

In the context of describing a tumor, the term differentiated refers to the extent to which the tumor cells resemble normal, healthy cells of the tissue from which the tumor originated. This characteristic is important when examining a malignant (cancerous) tumor as it provides insights into the potential behavior of the tumor and its likely response to treatment. The degree of differentiation is also referred to as the histologic grade of the tumor.

There are four main categories used to describe the differentiation of tumor cells:
  1. Well differentiated (low grade): Well differentiated tumors closely resemble normal cells in both structure and function. The cells maintain specialized features, and the organization of the tissue closely resembles the normal tissue. Well differentiated tumors are often associated with a more favorable prognosis, as they tend to grow more slowly and may respond better to treatment.
  2. Moderately differentiated (intermediate grade): Moderately differentiated tumors exhibit some characteristics of normal cells, but they also show some abnormalities. The degree of differentiation is intermediate between well differentiated and poorly differentiated. The prognosis is also intermediate.
  3. Poorly differentiated (high grade): Poorly differentiated tumors lack the normal features and organization seen in the mature, specialized cells of the tissue. Poorly differentiated tumors are often associated with a more aggressive course, faster growth, and may be less responsive to treatment. They also have a poorer prognosis compared to well differentiated and moderately differentiated tumors.
  4. Undifferentiated (high grade): Undifferentiated tumors show no organization and the cells are very abnormal-looking compared to mature, specialized cells. Undifferentiated tumors are almost always associated with an aggressive course, faster growth, and less response to treatment. They also have poorer prognoses compared to their better-differentiated counterparts.


The differentiation status of a tumor is typically determined through microscopic examination of tissue samples obtained through biopsy or surgery. This information, along with other factors such as tumor size, stage, and the presence of specific molecular markers, helps doctors predict the likely behavior of the cancer, and plan appropriate treatment strategies.

About this article

Doctors wrote this article to assist you in reading and comprehending your pathology report. Feel free to reach out to us with any questions about this article or your pathology report. To get a comprehensive introduction to your pathology report, read this article.

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Atlas of pathology
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