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1. The history suggest most possible cause could be
lipoma - lesion with fat content. Followed by spinal lesions, cystic lesion.
2.As its not hurting much - infective aetiology will be ruled out, absence of neurologic a rules out spinal causes.
3.If you are my patient, i would have examined first followed by an
ultrasound examination - it will help to assess the source of lesion, its nature ( cystic, solid), and where all the lesion is extending. FNAC - fine needle aspiration cytology - will be done to identify the cells.
4.After that if necessary
MRI will be needful - as MRI is good in anatomical delineation.
5.Depending on the imaging and pathological findings - needful action can be taken.
6.Suggest you to see you GP get the needful things done, mean while do not press, scratch the lesion, maintain local hygiene. Good luck.
Hope it helps you. Wish you a good health.
Anything to ask ? do not hesitate. Thank you.