How to biopsy a musculoskeletal tumour

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:

  1. Plan carefully in conjunction with the specialist surgical team
  2. Don’t contaminate new compartments or critical anatomical structures unnecessarily
  3. Needle biopsies are the “industry standard”
  4. 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
  5. Talk to the pathologist – some specimens go fresh
  6. 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.

What are the referral guidelines for soft tissue masses?

Soft tissue lumps are common: malignant ones are rare, but detecting them early is important. Delay in diagnosis is a significant problem in the treatment of sarcomas, as is unplanned excision. An unplanned excision occurs when a soft tissue lump is removed by a surgeon (or General Practitioner) without any thought about whether the lump might be malignant. (these are called “whoops” operations by sarcoma teams). Both of these problems can be minimised by using the referral guidelines.

A soft tissue lump exhibiting any of the following four following criteria should be considered malignant until proven otherwise:

  1. increasing in size
  2. size >5cm
  3. deep to the deep fascia
  4. painful

Patients with lumps such as these are best referred to a specialist centre for further investigation, which would start with imaging (eg USS or MRI).

UK soft tissue sarcoma guidance can be found here.

Guidance for referral to the London Sarcoma Service can be found here.

The North of England Bone and Soft Tissue Tumour Service has a fax for urgent referrals: 0191 223 1328.