### instruction:
If you are a doctor, please answer the medical questions based on the patient's description.

### input:
I am 73 yrs. old 250 lbs.. I have a small lump about the size of a ball (about half the size of a table tennis ball) on the outside of the left knee area, [Total Knee 2004]. It has grown in about 2 months It is hard and somewhat painful when touched, difficult to walk 200 yards or so. Orthopedic Surgeon opened the area, 4" incision and said, " I have not seen anything like this in all my years!" It was like a jell substance 3 colors orange,tan,red, all the way to the bone and no idea where it originated from! Altar Sound showed a solid Cyst. He removed what he could and stitched me up. This had all been sent to the lab, all negative for Cancer, Disease, and Infection! I still have a bulge on side of knee. It is still painful to walk any distance. He has me in therapy 2 weeks now, not much help also wearing a Knee brace. Therapist tested for strength which was very good.I was in DaNang, Vietnam, Agent Orange in 1963. I had Prostate Cancer, Gleason Score 8 Radical removed April 2010 3 Month later PSA 1.8 high risk fast growing, had 36 Radical Treatments Radiation. Could some of my problems be related to Agent Orange or another type of Virus? Help!!

### output:

Hi, Thanks for the query to Chat Doctor.-I studied your query in depth and understood your concerns.-Cause and Treatment-of the painful lump on side of knee--In your case the cause mostly is -due to Al-amyloidosis with cystic lump in the knee.?possibility of the Mets from the prostate cancer needs to be ruled out. Treatment would be according to the cause--Detox treatment for the Agent Orange -FDG Pet scan to find out the bone Mets -I would suggest Onco-Surgeon to deal with your case-Hope this would resolve this tricky problem. This would help you to plan treatment with your doctor.Don't worry and things will settle Hope this would resolve your query. Welcome further for any query in this regard. Wishing you a fast recovery.Don't forget to Write a good and strong review ASAP for the benefit of other patients. Have a Good Day.