the cellular differences between a metastatic tumor & a primary one

Question

I’m reading something which mentions that there is a difference, but not what it is or how the tumors are able to be told apart.

In: Biology

Answer 1

It is an issue of location, not structure.

A primary tumor appears to be made of local cells gone rogue, and the secondary tumor(s) appear to be non-local cells gone rogue.

For example, if you have primary pancreatic cancer, under a microscope it will look like pancreatic cells. But when cell breaks loose, gets moved around in the blood, and lodges in the liver, the secondary tumor that grows there will look like pancreatic cells, not liver cells.