Fine-needle aspiration biopsy
A doctor uses a thin, hollow needle to withdraw tissue from the lump. He or she then sends the tissue to a lab for microscopic analysis. The procedure takes about 30 minutes and is similar to drawing blood. A similar procedure - fine-needle aspiration - is typically performed to remove the fluid from a painful cyst, but it can also help distinguish a cyst from a solid mass.
Core needle biopsy
A radiologist or surgeon uses a hollow needle to remove tissue samples from a breast lump. As many as 15 samples, each about the size of a grain of rice, may be taken then sent to a pathologist to be analyzed for malignant cells. The advantage of a core needle biopsy is that it removes more tissue for analysis. Sometimes your radiologist or surgeon may use ultrasound to help guide the placement of the needle.