Tumour Biopsy Principles

PRINCIPLES OF TUMOUR BIOPSY:

1. Biopsy should be done only after clinical, laboratory, and roentgenographic examinations are complete. This will help in planning the placement of the biopsy incision. It will also help to make an accurate diagnosis
2. Place small incisions whenever possible, also use small capsular incisions over the tumour thus reducing bleeding
3. The biopsy track should be considered contaminated with tumor cells. Placement of the biopsy incision therefore is important because the biopsy track should also be excised en bloc with the tumor subsequently.
4. The surgeon should be familiar with incisions for limb salvage surgery, and also with standard and nonstandard amputation flaps.
5. If a tourniquet is used, the limb is elevated before inflation but should not be exsanguinated by compression because the latter may cause tumour spread.
6. Care should be taken to contaminate as little tissue as possible. Transverse incisions should be avoided since they are extremely difficult or impossible to excise with the specimen. The deep incision should go through a single muscle compartment (muscle belly) rather than through an intermuscular plane. Major neurovascular structures should be avoided. Care should be taken not to contaminate flaps. Minimal retraction should be utilized to limit soft tissue contamination.
7. If possible soft tissue extension of a bone lesion should be sampled
8. If a hole must be made in the bone, it should be round or longitudinally oval to minimize stress concentration and prevent a subsequent fracture. A fracture may preclude a subsequent limb salvage surgery. PMMA is plugged into the hole to contain a hematoma. Only minimal amount of PMMA needed to plug the hole should be used because excessive amounts will push the tumor up and down the bone.
9. Biopsy should be taken from the periphery of the lesion, which contains the most viable tissue. Biopsy material may be sent for culture and sensitivity if there is a doubt regarding infection
10. A frozen section should be sent intraoperatively to ensure that diagnostic tissue has been obtained. If a tourniquet has been used it should be deflated and meticulous haemostasis ensured before closure, since a hematoma would be contaminated with tumor cells.
11. Drains should not be used routinely. If a drain is used, it should exit in line with the incision so that the drain track also can be easily excised en bloc with the tumor. The wound should be closed tightly in layers.
12. When performing an open biopsy the operating surgeon should accompany the specimen to the pathologist if feasible and should discuss with the pathologist about clinical findings, imaging, intraoperative findings and the specimen.

Ref:
1. Mankin HJ, Mankin CJ, Simon MA: The hazards of the biopsy, revisited. Members of the Musculoskeletal Tumor Society. J Bone Joint Surg 1996; 78A:656.


IMMUNOHISTOCHEMISTRY:

 Immunohistochemical stains are used to identify certain specific intermediate filament proteins like desmin, vimentin, keratins, neurofilament, glial, fibrillary and lamin filament proteins.
 These can be appreciated in light microscopy after appropriate staining of the biopsy tissue
 Certain tumours have specific Immunohistochemical profiles that help in their identification
 Keratins (epithelial origin) are classically found in metastatic carcinomas. They are also seen in tumours containing epithelial elements like adamantinoma, synovial sarcoma, and epithelioid sarcoma.
 Vimentin (mesothelial origin) is positive in all sarcomas but occasionally negative in carcinomas
 Desmin and actin (muscle origin) is positive in tumours with myodifferentiation like rhabdomyomas, Rhabdomyosarcoma, leiomyomas and leiomyosarcomas. May also be present in desmoid tumours and primitive neuroectodermal tumours
 S- 100: the name of this protein is derived from the fact that it is soluble in 100% ammonium sulfate. It is positive in Histiocytosis-X
 Factor VIII related antigen (von Willebrand’s factor): these are positive in low-grade vascular lesion like hemangiomas and hemangioendotheliomas. But negative in high grade angiosarcomas