Biopsy Techniques – Principles
– sufficient tissue for diagnosis must be obtained
– the least traumatic method compatible with obtaining the diagnostic tissue should be used
* the procedure should be done in such as fashion as to not compromise the definitive management of the lesion; that is, it should be done with anticipation of the possible surgical resection. (Which is why it should be done by the surgeon who is going to ultimately treat the lesion)
Fine needle aspiration
– generates cells for cytologic examination only; do not get an idea of what the histologic architecture of the tumour is.
– good for soft tissue extensions of bone tumors that are likely metastatic or hematogenous in origin.
– requires a pathologist who is good at reading them!
Core needle biopsy: (eg. Tru-Cut core needle, Jamshita needle)
– generates more tissue that is more representative of the tumor
– allows for some evaluation of the tumour architecture
– good for biopsy of soft tissue sarcoma and soft tissue masses arising from probable primary bone tumours.
– time honoured method of getting specimen, particularly intra-osseous lesions
Principles of Performing the Open Biopsy
* the location should be chosen in anticipation of the incision needed for definitive surgical management, and should be done by the surgeon who will definitively manage the case
– incisions should be longitudinal (unless around the iliac crest)
– sharp dissection should be proceed directly to the tumour, with no elevation of skin or subcutaneous flaps.
– the deep dissection should go through the involved muscular compartment in anticipation of resecting it later; uninvolved anatomic compartments, routine intermuscular compartments, and neurovascular structures should be avoided. Basically, you gotta think that whatever you go though needs to come out later if doing a wide resection. If you go through an uninvolved muscle, it will need to come out. If you go between two muscles, they both need to come out. If you go through neurovascular plane, the neurovascular structure will need to come out.
– ie. Go from skin, through deep fascia, through underlying involved muscle, directly to tumour.
– if pseudocapsule is encountered – take pseudocapsule and tumour directly underneath – sharp dissection for everything to avoid crush artifact. Do not put in formalin!
– if no soft tissue component – make a round window in bone with Midas Rex and take specimen
Send specimen for stat frozen section – warn the pathologist ahead of time to be ready for the arrival of the specimen.
– is the tissue adequate to make a provisional diagnosis?
– is it representative of the lesion?
– does the diagnosis make sense?
– is there sufficient tissue to perform the remaining definitive histologic analysis and send for C&S?
– if tourniquet is used, deflate and obtain meticulous hemostatis to avoid wound hematoma
– wound closure should be done in multiple watertight layers to avoid further local contamination with hematoma
– if drain is used, bring it out in line of incision