Hi and welcome to HCM
As xray is normal bony lesion is ruled out. Other possibilities that may need to be considered include enlarged bursa, lipomas
, cysts, growths from underlying connective tissue
I would suggest getting this evaluated by an orthopedician for an accurate diagnosis and appropriate management. You may get the ultrasound
and FNAC (fine needle aspiration cytology) of lump under his/her guidance.
I do hope that you have found something helpful and informative and I will be glad to answer any further query.