A biopsy is the act of obtaining a piece of tissue from a tumor. It is then studied under a microscope by a pathologist (a physician who specializes in this area) to determine the type of tumor. Determining the type of tumor, and whether it is benign or malignant (cancerous) enables the doctors to determine the type of treatment. It is essential to have a biopsy before any surgery or treatment is administered. Biopsies can be performed in several ways. The safest and best way, in my opinion, is to have the biopsy performed in a minimally invasive manner (without having to cut the skin and make an incision) by means of a core-needle biopsy either in the operating room or under CT scan guidance whenever possible. This is not possible in all cases however. The choice of which type of biopsy should be performed is determined by many factors and should be left up to the discretion of the treating surgeon. Minimally invasive biopsies are also performed in the operating room by the surgeon often under fluoroscopic guidance
CORE NEEDLE BIOPSY
A core-needle biopsy uses a needle to get the tissue samples. It should be performed by the surgeon (orthopedic oncologist) who will treat the tumor or by a radiologist who is experienced with bone and muscle tumors and performing biopsies of them. The orthopedic oncologist and radiologist will discuss the tumor and approach prior to the biopsy and are in constant communication. The patient is given an injection of numbing medicine (usually lidocaine and marcaine) into the area of the tumor that will be biopsied. The patient is also administered medicines intravenously (into the vein) to relax the patient and prevent pain. During the procedure the patient is comfortable. The physician makes a single stab hole in the anesthetized area of the skin and aims the needle in multiple directions to sample different parts of the tumor. In most instances, the procedure will be performed under a CT (pronounced CAT) scan so the tumor can be seen and biopsied accurately. Ultrasound or other imaging modality may also be utilized. Once the specimen is obtained it takes about 3-4 days for the specimen to be processed and interpreted by the pathologist.
An Open Biopsy requires that the patient be brought to the operating room and the skin is cut (incision is made) over the tumor. A piece of tumor is cut out and sent to the pathologist to be studied under the microscope. An open biopsy requires the skin to heal postoperatively before starting any treatment. This is different from a core needle biopsy in which there is no healing time. There are also more complications such as infection, hematoma and fracture associated with an open biopsy. The risk of a local recurrence (the tumor coming back after it is surgically removed) is also higher following an open biopsy than with a core needle-biopsy.
The diagnostic accuracy rate of a core needle biopsy is the same or better than an open biopsy when performed at a center experienced with the treatment of these tumors (experienced orthopedic oncologist, musculoskeletal radiologist and surgical pathologist). About 90% of tumors are diagnosed accurately with this method. I therefore prefer core needle biopsy over an open biopsy for bone and muscle tumors (sarcomas of bone and soft tissues) because of its greater diagnostic accuracy and because it is associated with fewer complications. Open biopsies are usually reserved for unusual circumstances or when a diagnosis can not be rendered by a core needle biopsy (if more biopsy material will help make a diagnosis).
FINE NEEDLE ASPIRATION
FNA refers to Fine Needle Aspiration and should not be confused with a core needle biopsy. An FNA uses a very fine needle and does not obtain sufficient material for the diagnosis of bone and soft tissue tumors, bone sarcomas / soft tissue sarcomas. It is not used to biopsy tumors of the musculoskeletal system.