We went through something similar this last weekend with a friend of the family (3 yrs old). Went in for an arm x ray, and got admitted for a large abdominal mass.
They put a tube in to drain the swelling, but he went downhill quickly and was unable to communicate. His white blood cell count shot up (infection) and his remaining kidney shut down.
They pushed pretty hard for hospice, saying that the mass was almost certainly highly fatal advanced pancreatic cancer, and dialysis, if started, would be continuous for the rest of his life, and unlikely to work long, if at all.
The family opted for dialysis, and the nephrologist was visibly pissed off. Well, it turns out that the big problem was an infection induced when they put the initial tube in. Once antibiotics cleared that up, the kidney restarted.
A certain Monty Python skit comes to mind.