This is a classic exam question, and one every surgeon should know. Even if you think you won’t be doing biopsies, you need to stay out of trouble by being prepared.
The main issue is that sarcomas are highly implantable and the biopsy track needs to be removed with the tumour. That means that biopsies need to be planned with the surgical team who are going to remove the tumour. An inappropriate biopsy can jeopardise limb sparing surgery, particularly in difficult anatomical areas like the popliteal fossa and the pelvis.
Principles can be summarised as follows:
- Plan carefully in conjunction with the specialist surgical team
- Don’t contaminate new compartments or critical anatomical structures unnecessarily
- Needle biopsies are the “industry standard”
- If you do an open biopsy, use a vertical incision (easier to reexcise), make sure you have good haemostasis and if you need to drain, take it out close to or through the wound
- Talk to the pathologist – some specimens go fresh
- Make sure you get enough tissue
My preference is to use a trucut needle for soft tissue masses (usually in outpatients), or a bone needle (eg the Islam needle) for bone biopsies. Trucut biopsies are very good at distinguishing benign and malignant tumours, slightly less good at typing the tumour.
Excision biopsies are only performed for small (<5cm) superficial tumours which do not involve the deep fascia. If tumours like these turn out to be sarcomas, the whole scar can be excised along with the deep fascia.
Image guided biopsies are helpful in some anatomical areas or for vascular tumours.