Assuming the original biopsy was sent off to pathology, this was a benign lipomas. Lipomas can grew to massive sizes. This does not imply malignant transformation. In fact, many pathologists do not believe that a benigh lipoma can transform into a liposarcoma, the malignant version. They feel that the "lipoma" was actually a well differentiated liposarcoma at onset.
So I would not worry.
However, it would be prudent to have this excised before it becomes even more of a problem. Lioomas can insinuate themselves into muscle tissue and become much more difficult for the surgeon to excise. Eventually, if not already, you will have symptoms.
So, I would not worry but do get it taken care of please.