Objective: Giant cell tumours (GCTs) of the tendon sheets in fingers are rare. We therefore find it of interest to report on 5 cases identified in the Inuit population in Greenland within 16 months prior to this study.
Material and methods: The Inuit account for 56,000 people of the total population in Greenland. From November 2010 to 16 months prior to this study, we diagnosed 5 cases (0.6% of all orthopaedic operations) with a GCT of the flexor tendon sheet of a finger. The patients were aged between 10 and 54 years, and 4 were women. All of them had noticed slow-growing tumours over 3 or more years and were referred for a suspected ganglion.
Results: In two cases, the tumour was located at the distal interphalangeal (DIP) joint in the thumb and in one case at the third finger. Two other patients had tumours at the metacarpophalangeal (MCP) joint of the third finger and the thumb, respectively; one of these two had a communicating tumour to the DIP joint. The last patient had two tumours on the same finger, one at the MCP joint and the other at the DIP joint. In one case, the tumour had also eroded the cortex of the first phalanx of the thumb, and the largest tumour measured 5 cm.
Conclusion: GCTs of the flexor tendon sheets in fingers are rare. It could be a coincidence that we have seen 5 cases within a short period of time. It is not possible to identify past cases through a register. A tumour in a finger is not the most common location for a ganglion, especially not at the DIP level. Therefore, a large tumour at this location is more likely to be a GCT.
Keywords: Arctic; benign tumour; native; orthopaedic hand surgery; slow growing.