Biopsy a Bone Tumor Where It Will Be Removed
A biopsy done in the wrong place or along the wrong path can spread a sarcoma into healthy tissue and turn a limb-salvage resection into an amputation.
Key terminology
- Staging
- This workup maps how far a tumor extends, both within the limb and elsewhere in the body. Its result decides which operation the patient needs.
- Sarcoma center
- This hospital has an orthopedic oncologist, musculoskeletal radiologist and pathologist who treat bone and soft-tissue sarcomas as a team. It performs the definitive resection.
- Biopsy tract
- This path runs from the skin to the tumor along the needle or incision. Tumor cells can be left behind along it.
- Core needle biopsy
- This thin hollow needle, guided by CT or fluoroscopy, removes small cylinders of tissue. It avoids an open incision.
- Compartment
- This space holds a group of muscles wrapped in fascia, such as the front of the thigh. Its fascial walls act as barriers to tumor spread.
- Skeletal metastases
- This is carcinoma that has spread to bone from a primary such as lung, breast, kidney or prostate. It may look lytic or sclerotic on x-ray.
- Intramedullary nail
- This rod is passed down the marrow canal of a long bone to stabilize it. Reaming and nailing run instruments along the entire canal.
Takeaways
- Biopsy is the last step of staging and comes after imaging. Plain films and an MRI of the lesion come first, because bleeding and edema from a biopsy distort the MRI used to plan resection. Unplanned surgery skips this order. In a Japanese series of 97 unplanned soft-tissue sarcoma excisions, 45 had no MRI beforehand and 82 needed re-excision (Guedes and Nakagawa, Rev Assoc Med Bras 2024;70(suppl 1):e2024S131, PMID 38865550; Nakamura et al, In Vivo 2024;38:2712-2717, PMID 39477395).
- Biopsies done outside the treating center go wrong far more often. Errors were 2 to 12 times more common at referring hospitals than at treatment centers. The Musculoskeletal Tumor Society reviewed 329 sarcoma biopsies in 1982 and repeated the study with 597 patients in 1996. The results were nearly identical. Biopsy problems forced a more complex operation or added radiation or chemo in 19.3% (vs 18%), and 18 patients had an unnecessary amputation (Mankin et al, J Bone Joint Surg Am 1982;64:1121-1127, PMID 7130225; Mankin et al, J Bone Joint Surg Am 1996;78:656-663, PMID 8642021).
- An open biopsy outside a sarcoma center is the most likely to seed tumor along the tract. Open biopsies seeded the tract in 38% outside a sarcoma center vs 13% at the center. A Madrid center examined 180 resected biopsy tracts for tumor cells. Open biopsies seeded 32% of tracts and core needle biopsies seeded 0.8%. A seeded tract was associated with local recurrence-free survival of 11 vs 107 months. Harder tumors may have been biopsied open, so selection bias is possible (Barrientos-Ruiz et al, Clin Orthop Relat Res 2017;475:511-518, PMID 27655183).
- Image-guided core needle biopsy is now the usual first biopsy. At a referral center it reached 91.7% accuracy with a 1.0% complication rate, and open biopsy is kept for a nondiagnostic core. Open biopsy still yields more tissue. In low-grade central osteosarcoma, a subtle tumor, open biopsy was accurate in 91.3% and needle biopsy in only 35.3% (Crenn et al, Diagnostics 2021;11:1552, PMID 34573895; Khal et al, Bone Joint J 2024;106-B:99-106, PMID 38160683).
- The biopsy tract is treated as contaminated and excised en bloc with the tumor. The incision runs longitudinally in line with the planned resection (transverse incisions are contraindicated). It passes through 1 compartment and avoids intermuscular planes, the neurovascular bundle and the joint. Hemostasis is meticulous because a hematoma around a tumor is contaminated, and any drain exits within 1 cm of the incision (Guedes and Nakagawa, Rev Assoc Med Bras 2024;70(suppl 1):e2024S131, PMID 38865550).
- Needle tracts rarely seed, yet routine tract excision remains standard. Needle tracts were seeded in only 1.1% of 185 primary bone tumors. A cohort of 240 patients compared resections with and without excision of the needle tract. Local recurrence was 3.2% with excision and 1.8% without (p = 0.58). The authors call for multicenter studies before anyone drops tract excision (Gami et al, J Orthop 2024;48:13-19, PMID 38059219; Guedes and Nakagawa, Rev Assoc Med Bras 2024;70(suppl 1):e2024S131, PMID 38865550).
- A staged workup usually finds the primary behind a skeletal metastasis of unknown origin. It found the primary in 85% using history, exam, labs, chest and bone x-rays, bone scan, and CT of the chest, abdomen and pelvis. Chest x-ray found lung cancer in 43% and chest CT found another 15%. Biopsy alone could not name the primary in 65%. Over age 40 the differential is metastasis, myeloma and lymphoma (primary bone tumors less commonly) (Rougraff et al, J Bone Joint Surg Am 1993;75:1276-1281, PMID 8408149; Weber, J Am Acad Orthop Surg 2010;18:169-179, PMID 20190107).
- Do not put an intramedullary nail into an undiagnosed solitary lesion. Of 8 primary bone sarcomas fixed before referral, 6 ended in amputation. At a UK tumor center, 39.3% of patients with no cancer history and a solitary pathologic proximal femur fracture had a sarcoma. Biopsy has a cost too, since 32% of impending fractures completed after needle biopsy and no trial proves biopsy-first helps (Adams et al, Clin Orthop Relat Res 2009;467:519-525, PMID 18937020; Verspoor et al, Ann Surg Oncol 2023;30:7882-7891, PMID 37505350).