A breast lump is a mass that develops in the breast. Most breast lumps are benign (non-cancerous). Your doctor will likely perform a physical exam to evaluate a breast lump. To determine whether that lump is benign, your doctor will likely order a mammogram and breast ultrasound. Aug 16, - Breast self-exam, or regularly examining your breasts on your own, can be an important way to find a breast cancer early. Learn about breast.