Agree that it should be checked and to at least for a needle aspiration to be done and checked. It may just be a fatty tumor bi put I always, and suggest that, suspicious limos and growths be checked.
My poodles tend to get these as well. My Vet just does a needle aspiration and they go away. They usually come back in a different locations within a year then we repeat. The Vet can usually tell by looking at what comes out if it's anything to worry about.
I doubt if it's anything unusual. Poodles are predisposed to these types of cysts.
Hhhmmm... I worked for a vet for awhile (actually 4 vets in the practice), and there was always concern when a pet had a lump, especially if it was growing. Hard or soft didn't matter. Fine-needle aspirations were done (where they suck cells from inside the lump with a needle, and the contents examined under a microcope), and depending on what was found, the doctor might choose to drain it, surgically remove it, and/or have a sample sent off for cancer testing. The only reason one of our doctors would choose to do nothing was if the owner told them not to do anything, the animal was very old, or some other condition made treatment of the lump a bad idea. I hope this is helpful, and God Bless - Blu