Lump: question re:contents of cyst

[countrygoddess]

My GP, Daisy, came to us with 3 abscesses, all of which we had drained and/or removed. It was a long process for her to heal, both physically as well as behaviorally, because of all the trauma she went through with twice daily debridements for a good two months.

That was a year ago and last week I discovered a new lump on her back. This time I decided that I watch it and if it got bigger I would just do what I could to keep her comfortable rather than put her through such an awful ordeal again. I was even preparing for the eventuality of having her euthanized.

Tonight I checked on the lump and it wasn't much bigger (it was about the size and shape of a green grape) but it seemed more protuberant. She didn't seem to like having it touched so I decided to drain it some to take some of the pressure away. I carefully cut away the fur around the lump and then with clean, very sharp little scissors I quickly made a tiny little snip. She was such a brave girl through this!

Here's the thing--it wasn't an abscess. What came out was black as coal, thick, waxy, sticky, and musky-smelling. I decided it was a cyst as I squeezed out as much as I could (I got it all out and she seemed so relieved afterward that when I sat down to snuggle her she flopped on her side in my arms and nibbled happily on a carrot).

My question is this: I have been searching online for a description of the contents of sebaceous cysts and haven't found one. I was wondering if it was a collection of her scent/marking stuff (whatever that's called) but it was a good two inches up her back from her rump. Does my description of the contents sound like something any of you have seen? Does it sound like it was a sebaceous cyst? I washed the area with soap and water afterward and then drizzled some antibacterial wash over the little snip hole--do you think it will come back?