Thanks for using HCM
as
MRI is showing some fatty mass, it could be a
lipoma, its a benign condition, need not have to worry for that, pain you are getting could be due to
nerve which may be adjacent to fatty mass getting stimulated.
your doctor has advices surgery to see exact content of mass, you may need frozen section of mass to be done during procedure . better to undergo a procedure.
Have a good health.
Regards
Dr. Vidya