Biopsy Principles

Definition and Purpose

Biopsy is a critical diagnostic step in musculoskeletal oncology, providing tissue for histopathological, immunohistochemical, and molecular evaluation. It confirms diagnosis, determines tumor grade and type, and guides the surgical and oncologic treatment plan. A poorly planned biopsy can compromise definitive surgery and negatively affect patient outcomes.

Pre-Biopsy Evaluation

• Imaging first: All biopsies must be performed after complete imaging — plain radiographs, MRI, and CT if necessary — to define the lesion’s anatomy, extent, and relation to neurovascular structures.

• Multidisciplinary planning: The procedure should be planned collaboratively by the orthopaedic oncologist, radiologist, and pathologist to ensure diagnostic yield and safe resection later.

• Never biopsy without imaging: This avoids contamination of uninvolved compartments or incorrect approach that may preclude limb salvage.

Types of Biopsy

1. Core Needle Biopsy (CNB):
   Preferred method in most cases; minimally invasive and highly diagnostic (accuracy >90%).
   Multiple cores should be taken from viable, non-necrotic areas under image guidance (CT or USG).
   Especially suitable for deep-seated or pelvic lesions.

2. Incisional Biopsy:
   Indicated when core biopsy is non-diagnostic or tissue architecture is required.
   Performed through a small longitudinal incision in line with the planned surgical approach, directly over the lesion.
   The tract must be placed within the future resection field, as it will be excised en bloc during definitive surgery.

3. Excisional Biopsy:
   Reserved for small (<3 cm), superficial, easily accessible masses suspected to be benign.
   Should only be performed when wide excision can be achieved without compromising margins.

Technical Principles

• Approach: Follow the most direct route to the tumor; avoid crossing multiple compartments or uninvolved joints.

• Hemostasis: Essential to prevent hematoma and tumor seeding. Use minimal cautery and avoid suctioning into clean planes.

• Contamination control: Avoid biopsy through skin that will not be included in the definitive resection field.

• Suture placement: Mark the biopsy tract clearly to facilitate complete removal during tumor surgery.

• Specimen handling: Send fresh tissue in sterile saline for histopathology, microbiology, and molecular studies.

Common Pitfalls

• Inadequate imaging or unplanned approach leading to tumor spread along biopsy tract.

• Incision placed transversely instead of longitudinally, complicating excision.

• Sampling necrotic tissue, resulting in non-diagnostic pathology.

• Performing biopsy before referral to a specialized musculoskeletal oncology center.

Key Points

• Biopsy must be performed by — or in consultation with — the surgeon who will perform definitive tumor resection.

• Plan the biopsy incision as part of the final surgical approach.

• The entire biopsy tract must be excised with the tumor during definitive surgery.

• A well-planned biopsy enables accurate diagnosis and limb salvage; a poorly planned one can convert a resectable lesion into an inoperable case.

References

1. Mankin HJ, Lange TA, Spanier SS. The Hazards of Biopsy in Patients with Malignant Primary Bone and Soft-Tissue Tumors. J Bone Joint Surg Am. 1982;64(8):1121–1127.

2. Skrzynski MC, Biermann JS, Montag AG, Simon MA. Diagnostic Accuracy and Complications of Open vs Core Needle Biopsy. J Bone Joint Surg Am. 1996;78(5):644–649.

3. Puri A, Gulia A. Musculoskeletal Tumor Biopsy: Planning, Principles and Techniques. Indian J Orthop. 2022;56(1):21–28.

4. Enneking WF. Surgical Staging of Musculoskeletal Neoplasms. Clin Orthop Relat Res. 1986;(204):9–24.