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Soft tissue tumors of the foot - Biopsy Planning and Biopsy Techniques

Introduction: 

This learning module outlines the planning and performance of the biopsy of a soft tissue tumor in the foot and ankle.

Summary: 

This learning module shows how the correct planning and performance of the biopsy are crucial to the success of soft tissue tumor treatment. Some surgeons prefer to refer all tumors to a specialist without performing the biopsy due to the numerous medical and legal complexities. The pathologist should be included in biopsy planning process. Adequate longitudinal incisions are used to biopsy most tumors, and meticulous hemostasis is essential.

Topic Presentation: 

Many surgeons refer bone and soft tissue tumors to a specialist for definitive treatment, but some feel comfortable performing the diagnostic biopsy. However, improper timing, technique or management of the biopsy process can lead to significant problems. Complications of poorly planned biopsies include errors in diagnosis, nondiagnostic biopsy material, infection, hematoma, and contamination of nearby tissues. It has been shown that biopsy complications may lead to an otherwise avoidable amputation. Allegations of inappropriate treatment of cancer is one of the fastest growing areas of malpractice litigation in the United States. If there is any doubt, the patient should be promptly referred to an orthopedic oncologist or tumor specialist. 5

Therefore, it is essential to understand the proper techniques for biopsy, and appreciate the potential complications that can arise from this seemingly simple procedure. Pathological diagnosis can be difficult to make based on small samples. Therefore, open biopsy techniques are more likely to yield diagnostic material than needle biopsy or aspiration biopsy techniques. During the procedure, the pathologist should examine a frozen section of the biopsy material in order to insure that diagnostic material has been obtained. Biopsy should be performed at the last stage in the workup of the tumor. All of the diagnostic scans should proceed the biopsy, since the biopsy will alter the appearance of the tumor on the scans.

Biopsy should be made through adequate longitudinal incisions that approach the lesion most directly. Since the compartments of the foot are numerous, small, and incompletely bounded, it may be difficult to approach a lesion surgically without contaminating nearby normal tissues. Contamination of the neurovascular bundle near the medial malleolus is particularly problematic and may contribute to an unnecessary amputation. It is essential to prevent unintentional spread of the tumor due to post biopsy bleeding. The tourniquet should be released after the tumor is sampled, and measures should be taken to insure that the wound is completely dry. A moderate compressive dressing should be applied and the patient is made nonweightbearing with the extremity elevated for 3 or 4 days to prevent formation of a hematoma that may carry tumor cells and track under subcutaneous tissues or through intramuscular spaces, causing a wide zone of contaminated tissues.

Excisional biopsy is only rarely preferable for soft tissue tumors in the foot or ankle. Completely superficial soft tissue masses that are less than 2 cm in greatest dimension may be treated with excisional biopsy. During excisional biopsy, care should be taken that the tumor is not exposed or entered. The entire tumor, the surrounding capsule, and a small amount of surrounding normal soft tissue is taken en bloc. Excisional biopsy is never appropriate for large or deep soft tissue tumors. 6

Needle biopsy should be performed in centers where dedicated teams of surgeons and pathologists have perfected the technique, or for lesions where there is little doubt about the diagnosis and the biopsy is only needed to confirm what is already known. Needle biopsy or aspiration biopsy is an excellent choice for patients with a biopsy-proven cancer diagnosis who are suspected to have either a recurrence or a metastasis in the foot or ankle. In these cases, the histopathological characteristics of the cells aspirated from the new lesion can be matched against the tissue in the original biopsy.