I have a lump on my leg on the knee region..iv had for 9 yrs..have had it drained couple times..every time I end up on numerous iv.in arms..last time I had two iv.bags everyday for week..doctor said something about septic..and gangrene in same mumble. ..after he cut it open and black greenish yellow pus that has a very sweet sour smell came out..that s when nurses started running...why didn t he cut the dame thing out..it is right to the leg bone and it hurts...