It would be best to consult with a surgeon to rule out a cystic lesion or ganglion or skin nodule.
What is the exact site that you mention?
Are there any associated symptoms? Let the doctor decide whether you need to get an MRI done or not after a clinical examination.
Let us know if you have any other doubts and post us about what your doctor advises.
I have the same thing. Mine is one of the symtoms of my hypothyroidism. Is the lump soft? Maybe you shoulld have your thyroid checked.
At any rate you should see your doctor about it.