Dear doctors, my 13 year old daughter has knee pain and swelling above knee cap. Doctors say there is a fluid accumulation. Mantoux test was suggested and its result was highly positive with 35 mm bulge. Now doctor wants to perform biopsy and then start mtb treatment. Can't the fluid be tested instead of biopsy? Biopsy expenditure is high for my pocket. Chest x ray is clear. She has no cough, no weight loss and very active. X ray and mri also show no damage to bone or cartridges. Please advise if treatment has to started only after biopsy. Thanks.