Renal Calculi are stones found in the kidneys. Malign Renal Caluculus is the term used to describe worsening or even cancerous kidney stones. Percutaneous nephrolithotomy (removing stones from the kidney by a small puncture wound through the skin) or, rarely, open surgery may ultimately be necessary for large or complicated stones or stones which fail other less invasive attempts at treatment. Surgery is typically done from the back, through the ureter.