Hi and welcome to HCM Well, without a clinical evaluation it would be difficult to determine the cause of the lump. Possibilities that may need to be considered include enlarged bursa, lipomas, cysts, growths from underlying connective tissue etc. I would suggest getting this evaluated by an orthopedician for an accurate diagnosis and appropriate management. You may get the X-ray of the area affected 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. Take care.