Plasmacytoid cells

July 24, 2023

What are plasmacytoid cells?

In pathology, cells are described as plasmacytoid if they are round and if the nucleus (the part of the cell that holds the genetic material) is located to the side of the side. Pathologists often describe the location of the nucleus as eccentric or peripheral.

plasmacytoid cells
Plasmacytoid cells. This picture shows small groups of round plasmacytoid cells in a type of thyroid gland cancer called medullary thyroid carcinoma.

Why are they called plasmacytoid?

These cells are described as plasmacytoid because they look like plasma cells – a type of immune cell responsible for producing antibodies. Pathologists often perform additional tests such as immunohistochemistry to determine if a plasmacytoid cell is a true plasma cell or if it is another type of cell that has changed to look like a plasma cell.

Are plasmacytoid cells cancerous?

Plasmacytoid cells can be found in many different types of cancerous and non-cancerous human tumours. Pathologists use additional information including the location of the tumour, the other types of cells found with the plasmacytoid cells, the presence of mitotic figures (cells dividing to create new cells), the presence of invasion (whether the cells are spreading into surrounding tissue), and the results of special tests such as immunohistochemistry to help them decide if the plasmacytoid cells are cancerous or not.

What does plasmacytoid variant mean?

A cancerous tumour is described as a plasmacytoid variant if it contains large numbers of plasmacytoid cells – that is cells that look like plasma cells. Several different types of human cancers have a plasmacytoid variant and these cancers tend to behave in a more aggressive manner than the non-plasmacytoid variant of the tumour. For example, the plasmacytoid variant of urothelial carcinoma (a type of bladder cancer) is more likely to grow deeper into the bladder and spread to other parts of the body compared to urothelial carcinoma without plasmacytoid cells.

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