Abstract
The intra-articular injection of ascites fluid or of extracts derived from malignant tumors was shown to induce exudative joint lesions. The intra-articular injection of normal plasma did not have this effect. It is suggested that tumor secretes a permeability-enhancing agent. This substance promotes the extravasation of humoral or cellular elements into the joint spaces. A similar mechanism may underlie the development of pulmonary arthropathy or the formation of malignant effusions.