Thanks for writing in to us.
A lump in breast should always be investigated and ruled out for malignancy.
In your mother's situation, she should undergo mammography
of both breasts to study the lump. Depending on imaging features, the lump will be described as falling under a BI-RADS classification. BI-RADS classification tells us if a particular lump is totally benign, doubtful malignancy or malignant until proven otherwise.
In such scenario, the doctor may advise a needle aspiration under ultrasound guidance (FNAC) test where some cells from the lump will be sucked out and seen under microscope by a pathologist. Final treatment will depend on pathology findings.
Hope this helps.