What Causes Recurring Swelling And Fluid Retention Above Knee?

HI Doctor, MY brother has swelling and fluid retention above his one knee. He had a similar problem 3 years ago, but at that time swelling had started from both of his ankle and moved to knees. knees had water/fluid trapped, which was removed using syringe and he was given dose of anti biotics.



Now again he has problem in one knee. we got the fluid removed..about 50 ml and was tested. his lymphocyte is 96% in fluid. Doctor asked for TB test. we have got Chest Xray, elisa test IGg and IGm done, which are negative. also rheumatoid factor and uric acid is normal. we are not able to understand the problem. pls help.