Localized amyloid deposition in trigger finger.

Trigger finger is due to degeneration and thickening of the proximal portion (A1 pulley) of the flexor tendon sheath, which causes constriction of the flexor tendon. This study reports the presence of localized amyloid deposition in the tendon sheath of 11 of 47 cases (23%) of idiopathic primary trigger finger. Amyloid deposits were only found in patients aged over 46 years old and were present around cells and at sites of mucinous and fibrinoid degeneration which contained highly sulphated glycosaminoglycans. The pathogenic significance of these deposits is uncertain but their small size and presence only in middle-aged and elderly adults suggests that they represent a form of age-associated amyloid deposition.