Fibrinolytic activity in aneurysmal bone cysts.

Euglobulin fibrinolytic activity of cyst fluid from six patients with aneurysmal bone cysys was considerably higher than that of arterial and venous blood of the corresponding patients. The high fibrinolytic activity was associated with a very low concentration of fibrinogen and a low concentration of plasminogen. Correspondingly, a high plasminogen activator activity was found in cyst tissue related to endothelial lining. It is suggested that fibrinolysis is an important factor in the maintenance and expansion of the aneurysmal bone cyst.