What's wrong with my ferret?

My 3 year old ferret has an enlarged spleen. I don't have much money for testing to see exactly what's wrong with him but the vet said it might just be an enlarged spleen. We tryed Lupron for Adrenal Disease but it didn't work so he doesn't have that disease. Does anyone have or know someone who has a ferret with an enlarged spleen? Was it cancer or just nothing? Did it go away and is your ferret okay now?