The Importance of Biopsy in Sarcoma Diagnosis

Video: Biopsy for Sarcoma

Biopsy is critical, because the tissues that are removed during biopsy allow physicians to make a definite diagnosis. A physical exam, patient history, and imaging studies might suggest that a patient has a certain subtype of sarcoma, but that diagnosis can only be made after a pathologist examines the tumor's cells.

Tissue samples can be obtained through needle aspiration or through open surgical methods. Because many soft tissue sarcomas are easy for physicians to locate and feel, needle biopsy is often all that is necessary. Needle biopsies are frequently performed by radiologists under CT guidance.

Sometimes an incisional biopsy is necessary because it allows for the removal of more tissue. This type of biopsy involves making an incision in the skin and obtaining some pieces of the tumor for evaluation. Excisional biopsy (a biopsy that removes the entire tumor) should be avoided in most cases of suspected sarcomas, with rare exception. Instead, a well-planned resection surgery is preferred after the disease has been diagnosed and staged.

The Need for a Specialist

A full explanation of the use of biopsy in sarcoma cases can be found in the ESUN review article on Ewing's sarcoma.

The decision to remove part of the tumor or the entire tumor at the time of biopsy is extremely critical. The importance of having a sarcoma specialist either perform the actual biopsy or guide the treating surgeon in planning a biopsy can not be overstated.

The biopsy is often the first step to a successful limb-sparing procedure. The location of the biopsy incision and the technical aspects of obtaining tissue can have a major impact on subsequent operations.

Last revised: 8/2012
Last medical review: 12/2008

The Pathologist's Role in Sarcoma Diagnosis

Video: The Pathologist's Role in Cancer Care

A pathologist is a physician who uses scientifically-based laboratory methods to diagnose and characterize diseases. It is the pathologist who is ultimately responsible for making a sarcoma diagnosis based on the examination of tumor tissue.

Because the pathologist’s analysis of tissue from a patient’s tumor is absolutely critical in sarcoma treatment, sarcoma pathologists are specially trained in the diagnosis of these rare tumors. Correct identification of the specific sarcoma subtype is important because treatment protocols differ for various subtypes of sarcoma. Historically, sarcomas have been classified based on how they look under the microscope. Today it is also possible for pathologists to use molecular diagnosticsVideo to assist in diagnosis.

Video: The Pathologist's Role in Cancer Care

The pathologist’s reportVideo contains the diagnosis (the identification of the particular subtype of sarcoma), as well as information about the size, shape, and appearance of the tumor sample, and information about the completeness of resection for surgical specimens. This report might also come with a molecular pathology reportVideo, which indicates the presence or absence of specific genetic mutations.

Pathologists often practice as consultant physicians who develop and apply their knowledge of tissue and laboratory analyses to assist in the diagnosis and treatment of patients. As physicians and scientists, pathologists specializing in sarcoma employ clinical studies, models of disease, and basic science research to advance the understanding and treatment of sarcoma.

Last revised and reviewed: 8/2012

Grading and Staging Sarcomas

The pathologist's report provides an important piece of information called the tumor's grade. The grade refers to a tumor’s appearance under the microscope and is an indication of a tumor’s aggressiveness. High grade tumors behave more aggressively - they are more likely to spread or return after treatment than low grade tumors. Low grade tumors are less aggressive and have a lower chance of spreading or recurring. A tumor's grade is not a guarantee of its behavior, but it is one of the factors that doctors consider when making recommendations for treatment.

After the patient undergoes biopsy and a number of imaging studies, the stage of disease can be assigned. The stage indicates how far the sarcoma has progressed. A small cancer that is limited to one location is in an early stage. Disease that is spread throughout the body is in an advanced stage. It is important to understand that disease staging is not a guarantee of tumor behavior. Staging simply helps the treatment team to make the best recommendations for the patient.

Staging Systems Used for Sarcomas

The two staging systems that are most commonly used for sarcomas are the AJCC system and the Surgical Staging System of the Musculoskeletal Tumor Society (MSTS). This AJCC system classifies the tumor based upon histologic grade, tumor size, location as superficial or deep, and the presence or absence of metastatic disease (see Table 1).

Table 1: AJCC Staging System
Stage Histological
Size Location 
(Relative to fascia)
Systemic / Metastatic 
Disease Present
IA Low < 5cm Superficial or Deep No
IB Low ≥ 5cm Superficial No
IIA Low ≥ 5cm Deep No
IIB High < 5cm Superficial or Deep No
IIC High ≥ 5cm Superficial No
III High ≥ 5cm Deep No
IV Any Any Any Yes

The MSTS staging system classifies tumors based upon the histologic grade of the tumor, its local extent and the presence or absence of metastatic disease (see Table 2).

Table 2: MSTS Staging system
Stage Histological
Local Extent of Disease Systemic / Metastatic 
Disease Present
Ia Low Confined No
Ib Low Unconfined No
Ia High Confined No
Ib High Unconfined No
III Any Any Yes

Last revised: 8/2012
Last medical review: 12/2008