Hello, Thanks for writing to us. Without a clinical evaluation it would be difficult to determine the cause of the lump. Possibilities that may need to be considered include enlarged lipomas, cysts, growths from underlying connective tissue etc. Ii could be due to muscle pull or spasm. I would suggest getting this evaluated by an orthopedician for an accurate diagnosis and appropriate management. I do hope that you have found something helpful and I will be glad to answer any further query.