Giant cell tumour in the tendon sheath of the hand: importance of the type of lesion.

There are more diffuse giant cell tumours of the tendon sheath than we had expected, and we recommend excising them microscopically. We have treated 18 patients since 1988. They had two types of tumour: 10 nodular, and eight diffuse. We used a microscope to excise diffuse tumours. In the only case in which we did not use a microscope for a diffuse tumour, the tumour recurred. It spread to an adjacent joint in six diffuse tumours, but no nodular tumours. The detection of diffuse lesions was difficult without a microscope.