Orthopaedic oncology Generic structured oral examination question 1: Biopsy

EXAMINER: So how would you obtain a tissue diagnosis?

CANDIDATE: A tissue sample can be obtained by biopsy. In general terms this can be performed by excisional, incisional or percutaneous means, but I would not perform a biopsy without first having discussed the case with a bone tumour multidisciplinary team (MDT).

EXAMINER: Good. Let’s suppose you are the bone tumour surgeon now. When might you perform an excision biopsy?

The entire lesion is removed and the margins are often

marginal. Hence, this type of biopsy is really only applicable to benign lesions where the imaging has been diagnostic, for example lipomas, or where the lesion is small and superficial such that excision biopsy would not compromise later re- excision. However, if there is any doubt about the diagnosis

I would perform a percutaneous or incisional biopsy first.

EXAMINER: Ok, tell me how you would perform an incisional biopsy.

CANDIDATE: I would perform the procedure through a short longitudinal incision. I would plan the incision using the imaging, and position it such that the entire biopsy tract could be excised en bloc during the definitive resection, and such that it does not contaminate more than one compartment or key neurovascular structures. I would pay close attention to haemostasis and use minimal tissue dissection in order to minimize local tissue seeding.

EXAMINER: We perform most of our biopsies percutaneously now. Do you know any advantages or disadvantages to doing it this way?

CANDIDATE: I’ve seen biopsy performed by Tru-Cut needle. The procedure can be performed easily in clinic under local anaesthetic, which removes delay and the requirement for theatre time. Welker et al. have shown that it is safe, has a low complication rate and reliably provides enough tissue for diagnosis and treatment planning.¹ Other advantages are that it can be combined with imaging modalities, for example ultrasound for soft tissue lesions and CT for bony lesions. The disadvantage is that necrosis and mitotic rate is less reliable on core needle but this rarely affects management, and an incisional biopsy can always be performed subsequently if more information is required.