anaplasia

We talked yesterday about differentiation. Here’s another new word to learn: anaplasia. Anaplasia refers to a lack of differentiation in neoplastic cells. Well-differentiated tumors resemble their tissue of origin, whereas poorly-differentiated or undifferentiated (anaplastic) tumor cells appear primitive and lack specialization along any particular cell line. In general, benign tumors tend to be well-differentiated. Malignant tumors run the gamut from well-differentiated to undifferentiated.

Anaplasia is not the best choice of words here, but they didn’t ask me. Anaplasia means “to form backward,” which implies that the anaplastic cells are formed from well-differentiated cells that degenerate into an undifferentiated state. This is misleading. Cancers do not arise from reverse differentiation of normal cells, but from stem cells present in all tissues. So the term anaplasia is really a misnomer. I’m just saying.

Anaplastic cells have certain characteristics (the list below is adapted from Robbins).
1. pleomorphism (variation in size and shape).
2. abnormal nuclear morphology, such as hyperchromatism (very dark nuclei), irregular nuclear contours, an increased nuclear:cytoplasmic ratio, coarse chromatin, and nucleoli.
3. Mitoses (tons of them – or, more importantly, abnormal ones, like the ones at the tips of the arrows above).
4. Loss of polarity (disrupted orientation of cells; loss of architecture and organization)
5. Other things: tumor giant cells, ischemic necrosis (from tumor cells outgrowing their blood supply)

Can you find these characteristics in the above image? You should be able to find everything except ischemic necrosis!

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12 Responses to Anaplasia

  1. Arman Kuyumcian says:

    I have wanted to know for a while, since reading the passage in Robins which you have referred to… the pleomorphism of anaplasia… is that of the nuclei or of the whole cell?

  2. admin says:

    Pleomorphism refers to the entire cell. Pleomorphic cells vary a lot in overall size and shape – both in regard to cell size and shape and nuclear size and shape.

  3. Thank you for explaining anaplasia much better than my text book! I am in Pathophysiology and my book descibed it only as “a lack of differentiated features.” I fully understand the concept now!

  4. wondimu amado says:

    Thank you very much.because I Understand more about anaplasia.

  5. shadan says:

    What do u mean by’ streaming nuclear polarity’ .

  6. Kristine says:

    I don’t think I have that phrase in my post – but I can comment on a few things. In anaplasia, you have loss of polarity of cells. That means that instead of lining up like they should (for example, cells in glands usually have nuclei towards the basement membrane and more cytoplasm towards the apex of the cell), they lose their orientation (so cells in glands might have nuclei up towards the apex of the cell instead of at the bottom). Polarity is a word we use to describe entire cells, not nuclei. Streaming is a word used to describe a wavy or loose, linear arrangement of cells. Sometimes you see a streaming pattern in normal tissue (for example, in smooth muscle, the cells are arranged in a linear pattern and they look like they are streaming). Sometimes, though, when cells lose their polarity, the architecture is lost and instead of forming glands (or whatever it is they are supposed to form) they show a streaming pattern.

  7. m.hamdy says:

    thanks very much, i want to know the difference between polarity and palisading

  8. Kristine says:

    Good question! Polarity refers to the orientation of cells. For example, epithelial cells in glands often have nuclei that are close to the basal portion of the cell – and they are all lined up next to each other with their nuclei all in a row. So they are said to have “polarity.” As opposed to, say, lymphocytes in a lymph node, which are just there in sheets with no particular “up” or “down” to the cells. Palisading is when cells line up all in a row next to something. For example, you can see palisading of tumor cells around areas of necrosis – this means that the tumor cells are all lined up like little soldiers next to each other. Palisading implies the presence of some other structure – but polarity just refers to the orientation of cells (and usually, it’s used in reference to normal structures, like gut epithelium). Hope that helps!

  9. Ujwal says:

    What do we meant by pseudopalisading? I got confused by above answer of palisading with example of necrosis…thank you.

  10. Kristine says:

    Oh. Good question. Sometimes the word “pseudopalisading” is used when there is necrosis present (and the cells are lining up around the necrosis). True “palisading” would be in an area where there is not necrosis, and the tumor cells have just decided to line up in a row like that (like in schwannoma).

  11. mahtab says:

    Thank you very much,Doctor
    It was excellent much better than every text book.It shows you’ve understood it .
    A medicine student from Iran.

  12. Kabali says:

    Thanks a lot

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