The case is lipoma in the knee joint with vascular enhancemen. doctors said it must be removed and tested. but is biopsy necessary step? is it a must?

Smart step.: Lipoma is a benign fatty tumor, it looks a certain way, and is usually harmless, although it can grow in size and eventually be uncomfortable. Vascular enhancement means that you have a stronger vascular supply. Malignant tumors usually have a stronger vascular supply. A biopsy puts the mass under a microscope and makes sure it is in fact a lipoma. Purpose is to make sure.

Need surgery: Any space-occupying lesion in a joint will create problems as it grows, so it needs to come out.