anaplastic
Meaning of anaplastic: A pathologist's word for tumor cells so poorly formed that the tissue they grew out of can no longer be recognized.
Definition of anaplastic
Anaplastic describes cancer cells that have lost almost all resemblance to the normal cells they arose from. Under the microscope they show large dark irregular nuclei, cells of wildly varying size and shape, and many dividing figures. Anaplasia sits at the far end of the grading scale pathologists use, and it usually marks a tumor that grows and spreads quickly.
What is the pathologist looking at?
Normal tissue is orderly. Cells of one type look alike, sit in a recognizable arrangement, and carry the machinery that does the job of that organ. Cancer loosens all of it, and the word for how much of the original character survives is differentiation. In an anaplastic tumor almost none survives. Nuclei swell and stain darkly, taking up much more of the cell than they should. Cell size varies from one field to the next. Dividing cells are numerous and some divide abnormally. Giant cells with several nuclei appear. Without extra staining or genetic testing, the tissue of origin may be impossible to name.
How does grading work?
| Grade | What the tissue looks like |
|---|---|
| Well differentiated | Closely resembles the parent tissue, usually slower growing |
| Moderately differentiated | Still recognizable, but disordered |
| Poorly differentiated | Barely recognizable |
| Anaplastic or undifferentiated | No recognizable origin at all |
Grade describes how the cells look. Stage describes how far the disease has traveled. The two are separate, and a report gives both.
Why does the word appear inside tumor names?
Some diseases carry it in their title. Anaplastic thyroid cancer is one of the fastest growing human cancers, and there the name matches the behavior. Anaplastic large cell lymphoma is different: the name records the alarming appearance of its cells, yet many people with it respond very well to treatment, particularly the form that carries a specific gene rearrangement. The lesson is that anaplastic describes what the cells look like, and appearance alone does not settle what a disease will do.
Also known as
Used in a sentence
The report described anaplastic features with frequent abnormal mitotic figures.
Good to know
Anaplastic reports how cells look rather than how a disease behaves, and anaplastic large cell lymphoma shows the gap, since it often responds well to treatment despite the word in its name.
Word origin
Where “anaplastic” comes from
From the Greek ana, meaning backward, and plassein, meaning to form, describing tissue that appears formed backward toward an immature state.