Giant cell tumours of tendon sheath: classification and recurrence rate.

Forty-three consecutive cases of giant cell tumour of tendon sheath were included in a prospective study. The tumours were classified into two main types, depending on whether the entire tumour was, or was not, surrounded by one pseudocapsule as assessed by the surgeon during surgery. Each type was then sub-classified according to the thickness of the capsule, lobulation of the tumour, the presence of satellite lesions, and the diffuse or multicenteric nature of the tumour: these factors were also assessed by the surgeon. The mean follow-up period was 4 (range, 2-6) years. None of the type I tumours (n=30) recurred, but recurrence occurred in five out of 13 type II tumours. Second recurrences were seen with type II B and C, but not type II A tumours.