Dr & i feel hard lump on side of breast under arm, mamm and u.s. show nothing. my moms mom at my age had same kind lump was cancer, could it be same ?

Family history: If your mother had breast cancer at your age, then you are certainly at elevated risk, but you're already doing the right thing by getting examined with a mammogram and ultrasound. Keep doing this yearly if you are concerned and discuss the rest of your family history with your doctor. Any ovarian cancer? Maybe you might need genetic testing to determine your true risk.

Radioloically occult: Most breast cancers that are large enough to feel should be visible at mammography and/or ultrasound.There are several conditions that can cause lumps that are non-cancerous, such as fibrocystic condition, lipoma, prominent fat lobules, etc. Rarely, breast cancer can remain undetected by mammography and ultrasound.If you're still concerned, consider Breast MRI, second opinion or possibly biopsy.