Welcome to Health care magic.
1.History suggest that the lump / lesion in the back of the neck - possibilities could be a
lipoma ( fat content ) or a spinal involving lesion.
2.I would recommend you to get an
ultrasound examination of the lesion - that will help in identification of the lesion sours and its nature ( solid , cystic, tubular, mixed) and where all the lesion extending.
3.
MRI is definitive investigation of choice - its very good in anatomical delineation and spinal related pathologies.
4.Any one can be get wrong before getting its imaging findings.
5.An FNAC - fine needle aspiration cytology might be needed for histology findings - nature of cells.
6.After all these - if safe to excise - excision is treatment of choice. Good luck.
Hope it helps you. Wish you a good health.
Anything to ask ? do not hesitate. Thank you.