A tendon sheath tumour presenting as trigger finger.

The symptom of trigger finger may be caused by a variety of lesions. This report describes a trigger finger caused by a tumour in the tendon sheath. Trigger finger refers to transient arrest of motion in a finger. It may be caused by a variety of lesions such as those of the volar plate (Yancey & Howard, 1962) and joint capsule (Aldred, 1954), structural abnormalities of the metacarpal head (Flatt, 1961), lacerations of the flexor tendons (Janecki, 1976) and 'loose bodies' (Milford, 1971). Triggering as a result of tumour of the tendon sheath does not, however, appear to have been reported.