My pig Linney had a cyst or encapsulated abscess surgically removed from her lower back, just above the grease gland, last summer. They tried draining it first but it kept refilling and then the skin that had been covering it dried up and fell off so you could see the encapsulated lump right there at the surface- not much else to do but remove it. She went under general anasthesia and had the lump removed intact, and then the skin restitched over it. The vet used a type of stitches where the stitches are mainly buried under the skin so it's hard for the pigs to get at them. She actually did not pay much attention to the incision. We were probably lucky that it was right in the middle of her back low down and thus was hard for her to really reach for an extended period of time. It took awhile for the stitches to dissolve, and even longer for her fur to grow back from where they shaved her, but she recovered just fine. Not sure if the price will help as I don't know where you're living... I'm in Canada and the operation cost about two hundred dollars, plus the cost of antibiotics before and after. HTH a bit! Where is your piggie's cyst located?
sounds as though its in the same place as you describe.