If diagnostic imaging tests indicate there’s a growth in the brain, the only way to determine what type it is — and whether it’s cancerous — is to take a biopsy. In doing a biopsy, we remove a tissue sample from the affected area and send it to a pathologist to analyze under a microscope.

The pathologist determines what type of tumor it is and provides any other information that can help your doctors customize the most effective plan of care for you.

The location of the tumor in your head determines which biopsy approach would be best for you. Common biopsy approaches include:


In this procedure, your surgeon removes a piece of your skull bone to access the tumor and remove a sample of the tissue to the pathologist for analysis.

Needle Biopsy

Tumors located deep in your brain may require a fine needle aspiration biopsy, a procedure in which your surgeon uses 3-D imaging to guide a very thin needle into the tumor and remove a tissue sample. This procedure helps protect healthy brain tissue.


In this minimally invasive procedure, your surgeon uses a thin tube with a light and lens on its tip called an endoscope to operate through a small opening in the skull and retrieve tissue for the pathologist to analyze.

Lumbar Puncture (Spinal Tap)

When performing a spinal tap, we remove a sample of spinal fluid; abnormal cells in this fluid may indicate the presence of a tumor. Learn more about this procedure.

At MSK, pathologists analyze DNA in the tumor sample from the biopsy and look for specific mutations associated with particular brain tumor subtypes. This information can inform which chemotherapies and other treatments will be most effective in managing your cancer.