Wrist mass in a 93-year-old woman

A 93-year-old woman presented electively for transaortic valve implantation (TAVI), for severe aortic stenosis. She had a history of hypertension and hypothyroidism, and she was taking clopidogrel, antihypertensives and levothyroxine. In preparation for her TAVI procedure she underwent coronary angiography 4 months previously. Her coronary angiogram revealed severe three vessel disease, however, the consensus from the multidisciplinary team meeting, at that time, was to manage the coronary disease medically. Physical examination revealed a large, non-tender swelling on the volar aspect of her wrist (figure 1). The swelling had progressively enlarged in size over the preceding 4 months. Duplex ultrasonography was performed, but was technically difficult. Turbulent bidirectional flow was seen within the wrist swelling, however the connecting tract from which the flow originated was not adequately visualised. The greyscale ultrasound is shown (figure 1).

Figure 1

The panel on the left shows the swelling on the volar aspect of the wrist. The panel on the right shows the grey scale ultrasound image of the swelling at the wrist.

What is the next most appropriate management step?